Implement `textDocument/formatting`

[zaucy]

At least for bazel files spawning buildifier when an lsp formatting request is made could be sufficient.

[withered-magic]

I think this makes sense! I currently use Bazel VSCode extension which currently takes care of calling buildifier but can see this being useful for other editors, just need to do some research to see if this could potentially cause conflicts with the default VSCode functionality and if so make it an opt-in feature

[steeve]

hey folks, i have implemented it in #401, it works great with Zed

[joelreymont]

Any ETA for merging this?

I'd love to use it with Helix!