all: more linters (#24783)

This enables the following linters

- typecheck
- unused
- staticcheck
- bidichk
- durationcheck
- exportloopref
- gosec

WIth a few exceptions.

- We use a deprecated protobuf in trezor. I didn't want to mess with that, since I cannot meaningfully test any changes there.
- The deprecated TypeMux is used in a few places still, so the warning for it is silenced for now.
- Using string type in context.WithValue is apparently wrong, one should use a custom type, to prevent collisions between different places in the hierarchy of callers. That should be fixed at some point, but may require some attention.
- The warnings for using weak random generator are squashed, since we use a lot of random without need for cryptographic guarantees.

trie/proof.go

@@ -367,11 +367,12 @@ func unset(parent node, child node, key []byte, pos int, removeLeft bool) error
 					// branch. The parent must be a fullnode.
 					fn := parent.(*fullNode)
 					fn.Children[key[pos-1]] = nil
-				} else {
-					// The key of fork shortnode is greater than the
-					// path(it doesn't belong to the range), keep
-					// it with the cached hash available.
 				}
+				//else {
+				// The key of fork shortnode is greater than the
+				// path(it doesn't belong to the range), keep
+				// it with the cached hash available.
+				//}
 			} else {
 				if bytes.Compare(cld.Key, key[pos:]) > 0 {
 					// The key of fork shortnode is greater than the
@@ -379,11 +380,12 @@ func unset(parent node, child node, key []byte, pos int, removeLeft bool) error
 					// branch. The parent must be a fullnode.
 					fn := parent.(*fullNode)
 					fn.Children[key[pos-1]] = nil
-				} else {
-					// The key of fork shortnode is less than the
-					// path(it doesn't belong to the range), keep
-					// it with the cached hash available.
 				}
+				//else {
+				// The key of fork shortnode is less than the
+				// path(it doesn't belong to the range), keep
+				// it with the cached hash available.
+				//}
 			}
 			return nil
 		}

trie/utils.go

@@ -50,6 +50,7 @@ func newTracer() *tracer {
 	}
 }
 
+/*
 // onRead tracks the newly loaded trie node and caches the rlp-encoded blob internally.
 // Don't change the value outside of function since it's not deep-copied.
 func (t *tracer) onRead(key []byte, val []byte) {
@@ -59,6 +60,7 @@ func (t *tracer) onRead(key []byte, val []byte) {
 	}
 	t.origin[string(key)] = val
 }
+*/
 
 // onInsert tracks the newly inserted trie node. If it's already in the deletion set
 // (resurrected node), then just wipe it from the deletion set as the "untouched".
@@ -115,6 +117,7 @@ func (t *tracer) deleteList() [][]byte {
 	return ret
 }
 
+/*
 // getPrev returns the cached original value of the specified node.
 func (t *tracer) getPrev(key []byte) []byte {
 	// Don't panic on uninitialized tracer, it's possible in testing.
@@ -123,6 +126,7 @@ func (t *tracer) getPrev(key []byte) []byte {
 	}
 	return t.origin[string(key)]
 }
+*/
 
 // reset clears the content tracked by tracer.
 func (t *tracer) reset() {