Implement non-function type alias support in language/co19 tests

[leafpetersen]

This issue tracks support of the non-function type alias feature. See the enclosing meta-issue for details.

cc @franklinyow @eernstg @mit-mit

[eernstg]

@sgrekhov, @iarkh, what is the current status?

[sgrekhov]

@eernstg we have non-function type aliases tests in co19. We simply need to enable these tests in .status files. Do you want me to do it now?

[eernstg]

@sgrekhov, yes please!

[sgrekhov]

https://dart-review.googlesource.com/c/sdk/+/185082

[eernstg]

I'll make sure that we have language tests for cyclicity.

[eernstg]

Type alias cyclicity tests landed as https://dart-review.googlesource.com/186290.