nixd/foldingRange: support `textDocument/foldingRange`

[inclyc]

https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_foldingRange

[AkechiShiro]

Hi again @inclyc, what is needed to work on this first issue, it seems the previous assigned to me, got solved by someone else, they were more proactive than me.

For this one, there is the need to add support for the textDocument_foldingRange, there seems to be a list of exports FoldingRangeClientCapabilities and, adding support means that we have somewhere in our codebase all these capabilities ??

[inclyc]

Hi again @inclyc, what is needed to work on this first issue, it seems the previous assigned to me, got solved by someone else, they were more proactive than me.

For this one, there is the need to add support for the textDocument_foldingRange, there seems to be a list of exports FoldingRangeClientCapabilities and, adding support means that we have somewhere in our codebase all these capabilities ??

Thanks for your contribution!

I'm working on a big diff #257 that will change the frontend, which will affect this issue. For now I think we need to wait for #257 before making any changes, to avoid git conflicts.