feat: add a first code-action quickfix (add missing attributes)

[kevineor]

Implementation for a first LS CodeAction quickfix feature

Related issues

hashicorp/vscode-terraform#801
#1530

Proposal

The implementation relies on Diagnostics data property : https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#diagnostic

This property is stated as an extra data that is kept between textDocument/publishDiagnostics notifications and textDocument/codeAction requests, this permits to avoid the need of parsing again the document.

This could be proposed for other issues that are pushed through Diagnostics

Actual state

Currently filling the missing attribute using a null value, it may be possible to use the default value, when one is provided.

[hashicorp-cla]

All committers have signed the CLA.

[jeremychauvet]

Waw!

[radeksimko]

There is a plan for introducing some abstraction layers first before we begin to introduce more code actions. This is to ensure they all stay reasonably maintainable as we can anticipate many more will come.

I outlined some more details in #1575 but this is mostly for transparency, not in the anticipation of an external contributor picking up any of that work. We do expect external contributors like you to participate in maintaining those individual code actions however, which will hopefully make use of the abstraction layers.

I know this may not be the answer you were hoping for but I prefer to be honest and open, even if that implies high likelihood of the PR being closed in the near term and/or need significant rewrite later.

For now I'm putting it on hold and a team member will revisit this PR later. I cannot commit to any timeline at this point unfortunately.

Thank you for your effort and understanding!