Tracking issue for non-function type aliases

[leafpetersen]

This issue is for tracking implementation of the non-function type aliases feature.

The implementation plan for this issue is here.

TODO:

• Issue for implementation in dart2js.
• Issue for implementation in DDC.
• Issue for implementation in the VM.
• Issue for implementation in CFE.
• Issue for implementation in Analyzer.
• Issue for implementation in IntelliJ.
• Issue for implementation in syntax highlighters
  • Github syntax highlighting.
  • Github grammar for use with VS Code.
  • highlight.js support (api.dart.dev, api.pub.dev, Dartdoc):
  • CodeMirror support (DartPad).
• Issue for support in linter.
• Issue for implementation in Kythe.
• Issue for implementation in Cider.
• Issue for implementation in Dartfmt.
• Issue for implementation in Dartdoc.
• Issue for implementation in build systems and Angular compiler.
• Issue for VM Service support.
• Issue for web debugging support.
• Issue for language tests written.
• Issue for documentation.
• Issue for tests validated as passing.
• Issue for core library updates.