Add env_file + ConfigMaps feature to Kompose

When using env_file with Docker Compose, a ConfigMap will be generated

For example:

```sh
▶ ./kompose convert -f
script/test/fixtures/configmaps/docker-compose.yml
INFO Kubernetes file "redis-service.yaml" created
INFO Kubernetes file "redis-deployment.yaml" created
INFO Kubernetes file "foo-env-configmap.yaml" created
INFO Kubernetes file "bar-env-configmap.yaml" created
```

File:

```yaml
version: '3'

services:
  redis:
    image: 'bitnami/redis:latest'
    environment:
      - ALLOW_EMPTY_PASSWORD=no
    # Env file will override environment / warn!
    env_file:
      - "foo.env"
      - bar.env
    labels:
      kompose.service.type: nodeport
    ports:
      - '6379:6379'
```

To:

```yaml
apiVersion: v1
data:
  ALLOW_EMPTY_PASSWORD: "yes"
kind: ConfigMap
metadata:
  creationTimestamp: null
  name: foo-env
```

```yaml
...
      - env:
        - name: ALLOW_EMPTY_PASSWORD
          valueFrom:
            configMapKeyRef:
              key: ALLOW_EMPTY_PASSWORD
              name: foo-env
```

script/test/cmd/tests.sh

@@ -418,6 +418,12 @@ cmd="kompose convert --stdout -j --provider=openshift -f $KOMPOSE_ROOT/script/te
 sed -e "s;%VERSION%;$version;g" -e "s;%CMD%;$cmd;g"  "$KOMPOSE_ROOT/script/test/fixtures/healthcheck/output-os-template.json" > /tmp/output-os.json
 convert::expect_success "kompose convert --stdout -j --provider=openshift -f $KOMPOSE_ROOT/script/test/fixtures/healthcheck/docker-compose.yaml" "/tmp/output-os.json"
 
+# Test ConfigMap generation
+cmd="kompose convert --stdout -j -f $KOMPOSE_ROOT/script/test/fixtures/configmap/docker-compose.yaml"
+sed -e "s;%VERSION%;$version;g" -e "s;%CMD%;$cmd;g"  "$KOMPOSE_ROOT/script/test/fixtures/configmap/output-k8s-template.json" > /tmp/output-k8s.json
+convert::expect_success "kompose convert --stdout -j -f $KOMPOSE_ROOT/script/test/fixtures/configmap/docker-compose.yaml" "/tmp/output-k8s.json"
+
+
 # Test V3 Support of Docker Compose
 
 # Test deploy mode: global

script/test/fixtures/configmap/bar.env

@@ -0,0 +1,3 @@
+# Multi-line test
+FOO=BAR
+BAR=FOO

script/test/fixtures/configmap/docker-compose.yaml

@@ -0,0 +1,15 @@
+version: '3'
+
+services:
+  redis:
+    image: 'bitnami/redis:latest'
+    environment:
+      - ALLOW_EMPTY_PASSWORD=no
+    # Env file will override environment / warn!
+    env_file:
+      - "foo.env"
+      - bar.env
+    labels:
+      kompose.service.type: nodeport
+    ports:
+      - '6379:6379'

script/test/fixtures/configmap/foo.env

@@ -0,0 +1,2 @@
+# Test comment!
+ALLOW_EMPTY_PASSWORD=yes

script/test/fixtures/configmap/output-k8s-template.json

@@ -0,0 +1,135 @@
+{
+  "kind": "List",
+  "apiVersion": "v1",
+  "metadata": {},
+  "items": [
+    {
+      "kind": "Service",
+      "apiVersion": "v1",
+      "metadata": {
+        "name": "redis",
+        "creationTimestamp": null,
+        "labels": {
+          "io.kompose.service": "redis"
+        },
+        "annotations": {
+          "kompose.cmd": "%CMD%",
+          "kompose.service.type": "nodeport",
+          "kompose.version": "%VERSION%"
+        }
+      },
+      "spec": {
+        "ports": [
+          {
+            "name": "6379",
+            "port": 6379,
+            "targetPort": 6379
+          }
+        ],
+        "selector": {
+          "io.kompose.service": "redis"
+        },
+        "type": "NodePort"
+      },
+      "status": {
+        "loadBalancer": {}
+      }
+    },
+    {
+      "kind": "Deployment",
+      "apiVersion": "extensions/v1beta1",
+      "metadata": {
+        "name": "redis",
+        "creationTimestamp": null,
+        "labels": {
+          "io.kompose.service": "redis"
+        },
+        "annotations": {
+          "kompose.cmd": "%CMD%",
+          "kompose.service.type": "nodeport",
+          "kompose.version": "%VERSION%"
+        }
+      },
+      "spec": {
+        "replicas": 1,
+        "template": {
+          "metadata": {
+            "creationTimestamp": null,
+            "labels": {
+              "io.kompose.service": "redis"
+            }
+          },
+          "spec": {
+            "containers": [
+              {
+                "name": "redis",
+                "image": "bitnami/redis:latest",
+                "ports": [
+                  {
+                    "containerPort": 6379
+                  }
+                ],
+                "env": [
+                  {
+                    "name": "ALLOW_EMPTY_PASSWORD",
+                    "valueFrom": {
+                      "configMapKeyRef": {
+                        "name": "foo-env",
+                        "key": "ALLOW_EMPTY_PASSWORD"
+                      }
+                    }
+                  },
+                  {
+                    "name": "BAR",
+                    "valueFrom": {
+                      "configMapKeyRef": {
+                        "name": "bar-env",
+                        "key": "BAR"
+                      }
+                    }
+                  },
+                  {
+                    "name": "FOO",
+                    "valueFrom": {
+                      "configMapKeyRef": {
+                        "name": "bar-env",
+                        "key": "FOO"
+                      }
+                    }
+                  }
+                ],
+                "resources": {}
+              }
+            ],
+            "restartPolicy": "Always"
+          }
+        },
+        "strategy": {}
+      },
+      "status": {}
+    },
+    {
+      "kind": "ConfigMap",
+      "apiVersion": "v1",
+      "metadata": {
+        "name": "foo-env",
+        "creationTimestamp": null
+      },
+      "data": {
+        "ALLOW_EMPTY_PASSWORD": "yes"
+      }
+    },
+    {
+      "kind": "ConfigMap",
+      "apiVersion": "v1",
+      "metadata": {
+        "name": "bar-env",
+        "creationTimestamp": null
+      },
+      "data": {
+        "BAR": "FOO",
+        "FOO": "BAR"
+      }
+    }
+  ]
+}