fix(dart): hide internal fields in ctor

[isidorowiczdev]

Fix Dart generator so internal fields stay out of public all-args constructor. Reason: current generator leaks @internal field into public API, unlike Java, and smoke tests show broken output.

[pwrobeldev]

As discussed offline -- besides the problem with all args ctor there seems to also be a problem when we have at least 1 initialized field in the structure.

Please have a look at the following input from our smoke tests:

• https://github.com/heremaps/gluecodium/blob/master/gluecodium/src/test/resources/smoke/visibility_attribute/input/VisibilityInternal.lime#L94

And the corresponding output for Dart:

• https://github.com/heremaps/gluecodium/blob/master/gluecodium/src/test/resources/smoke/visibility_attribute/output/dart/lib/src/smoke/public_struct_with_non_default_internal_field.dart#L9

In the output file you can see that all args ctor is private, but initialized fields ctor that is public exposes the internal field and takes its value -- this does not seem correct.

[Hsilgos]

Hide whole constructor because of one field?
May be filter it out like fields with default values?

[pwrobeldev]

Unfortunately, this breaks the functional tests. They do not compile. We need to analyze the logic of generation constructors, because the fix may not be trivial.

[pwrobeldev]

Hide whole constructor because of one field? May be filter it out like fields with default values?

@Hsilgos -- is the proposal to filter the internal field from the constructor's parameters list?

If that's the proposal, then I have one question:

• How will that field be initialized if it does not have default value set?

If I understand correctly, if we filtered such field from the constructor then it would be uninitialized.