feat: support refactoring opportunities

[wesleimp]

There're some refactoring opportunities that could be supported

• [ ] PipeChainStart - https://hexdocs.pm/credo/Credo.Check.Refactor.PipeChainStart.html
• [ ] UnlessWithElse - https://hexdocs.pm/credo/Credo.Check.Refactor.UnlessWithElse.html
• [ ] FilterCount - https://hexdocs.pm/credo/Credo.Check.Refactor.FilterCount.html
• [ ] FilterFilter - https://hexdocs.pm/credo/Credo.Check.Refactor.FilterFilter.html

[mhanberg]

@wesleimp can you split these into 4 separate issues for me?

[wesleimp]

@wesleimp can you split these into 4 separate issues for me?

Yes, I'll do this ASAP

[mhanberg]

Thanks, no rush at all.

[wesleimp]

Closing this due to #16 #17 #18 #19