Dart: do not export nested types defined in internal types

[pwrobeldev]

In the case of Dart the nested types defined in types
annotated as @Internal were exported. This was invalid
behaviour -- such types shall not have been exported.

The root cause for that was usage of 'CommonGeneratorPredicates'
to check if type is internal. In the case of Dart there is no
type nesting and all types are outside. The common version of
predicate did not check if any of parent types uses @Internal.

This change:

• moves Dart specific logic responsible for checking if LimeType
  is internal from DartVisibilityResolver.kt to DartGeneratorPredicates.kt
• injects the predicate to DartVisibilityResolver via constructor in order
  to preserve the existing behaviour of checking if type is internal
• fixes the way how DartGenerator.generateDart() selects types to export by
  using Dart specific predicate instead of the generic one

Note: this change adjusts smoke tests to show, that the internal types like
structs, classes and lambdas are no longer exported when their parent
type is @Internal.

[pwrobeldev]

Notes for reviewers -- this PR is split into 2 commits:

• the first one is big, but it contains only extension of smoke tests to show the invalid behavior of the generator -- the most important file is smoke.dart
• the second one is small and it contains the actual fix for the problem

[pwrobeldev]

Another important note -- even though the commit uses @Internal annotation it is not visible in the generated code. That's the desired behavior of Gluecodium. It is expected. Please see the linked comment for the explanation.

#1333 (comment)