Full support for Delphi 12

[cirras]

This PR finishes implementing support for Delphi 12.

[fourls]

Sorry for the delay in reviewing - looks great for the most part! Just a couple of questions and a changelog improvement.

There's been a few changes in master since this branch forked, so would be good to get it rebased on master as well.

[fourls]

Code change looks good, but it seems to have significantly increased the execution time of the delphi-checks tests - on GitHub Actions it's doubled, going from 4m 50s in master to 9m 46s on this branch. Ideally we'd get this back down to a similar amount of time before merging.

Initial analysis and profiling suggests that it's due to an uptick in the volume of runtime classes generated for weak alias types.

[cirras]

Code change looks good, but it seems to have significantly increased the execution time of the delphi-checks tests - on GitHub Actions it's doubled, going from 4m 50s in master to 9m 46s on this branch. Ideally we'd get this back down to a similar amount of time before merging.

Initial analysis and profiling suggests that it's due to an uptick in the volume of runtime classes generated for weak alias types.

This was because we started generating weak aliases as part of TypeFactoryImpl construction.
We used to cache type alias classes per TypeAliasGenerator - that cache is now static and the classes are generated only once.

[fourls]

All looks good now! Tests are back down to usual durations (perhaps even slightly faster).
Looks like we can close the book on Delphi 12 compatibility now 😄