Add CLI option to choose model checker engine

test/cmdlineTests/standard_model_checker_engine_all/input.json

@@ -0,0 +1,14 @@
+{
+	"language": "Solidity",
+	"sources":
+	{
+		"A":
+		{
+			"content": "// SPDX-License-Identifier: GPL-3.0\npragma solidity >=0.0;\npragma experimental SMTChecker;\ncontract C { function f(uint x) public pure { assert(x > 0); } }"
+		}
+	},
+	"settings":
+	{
+		"modelCheckerEngine": "all"
+	}
+}