Better Codefix onboarding process

[TheAngryByrd]

Creating a codefix still seems to have a high bar to entry. We should try lowering that as much as possible.

High Level Ideas:

• Have some type of scaffolding tool to generate:
  • Give a name for a codefix
  • Give a possible diagnostic code for a codefix
  • Codefixes files in src and test
  • Codefix file should:
  • filter by diagnostic code
  • be able to get the AST and use the Visitor to get at a symbol
  • return the range and a sample fix
  • comments with links to various tools/topic that may be useful for dealing with ASTs (like fantomas online tool)
  • Codefix tests should
  • Be able to test against this new scaffolded codefix
  • Be focused initially so it's easy to dotnet test
  • Unsure if we should make the test pass or fail initially
  • Maybe automatically add it to the LSPServers

[TheAngryByrd]

cc @nojaf @dawedawe

[nojaf]

Give a possible diagnostic code for a codefix

This would be a nice follow-up thought.