Simplify `handleMaybeM` in `hls-plugin-api`

[July541]

Currently, we have many use cases for handleMaybeM like the following, and it gradually being our regular mode of running action. I propose that can simplify it and just pass the action type itself. Like handleMaybeM' TypeCheck nfp to get the same effect as handleMaybeM.

[michaelpj]

I agree, it would be nice to refactor this stuff, it's very verbose and everywhere. I wonder if we should actually give plugins a proper monad to run in rather than Either String _ or whatever they currently have 🤔

[July541]

Either String _ is acceptable, but a new design monad may be more suitable for our application.