[Feat]: Initial Support for LSP Code Actions

[tm1000]

This adds initial support for Code Actions in the Language Server.

Code actions allow a user in their respective IDE to right click an error and implement a "quickfix".

The initial work only implements the ability to suppress errors. The reasoning for this is because it seems difficult in Psalms current state to query the diff from Psalter while running in the Language server (More investigation needs to be done here.

Here's an example of this working in VSCode using: https://github.com/psalm/psalm-vscode-plugin

Screen.Recording.2021-12-30.at.3.16.45.PM.mov

The next steps after this would be to enable the ability to auto fix issues from Psalter.

[tm1000]

@joehoyle thoughts? As you've worked on the LSP in the past as well

[weirdan]

Thanks!