Add supported commands in server capabilities - #11850

Summary

This PR updates the server capabilities to include the commands that Ruff supports. This is similar to how there's a list of possible code actions supported by the server.

I noticed this when I was trying to find whether Helix supported workspace commands or not based on Jane's comment (#11831 (comment)) and I found the :lsp-workspace-command in the editor but it didn't show up anything in the picker.

So, I looked at the implementation in Helix (https://github.com/helix-editor/helix/blob/9c479e6d2de3bca9dec304f9182cee2b1c0ad766/helix-term/src/commands/typed.rs#L1372-L1384) which made me realize that Ruff doesn't provide this in its capabilities. Currently, this does require ruff to be first in the list of language servers in the user config but that should be resolved by helix-editor/helix#10176. So, the following config should work:

[[language]]
name = "python"
# Ruff should come first until https://github.com/helix-editor/helix/pull/10176 is released
language-servers = ["ruff", "pyright"]

Test Plan

1. Neovim's server capabilities output should include the supported commands:

  executeCommandProvider = {                                                                                                                          
    commands = { "ruff.applyFormat", "ruff.applyAutofix", "ruff.applyOrganizeImports", "ruff.printDebugInformation" },                                
    workDoneProgress = false                                                                                                                          
  },

2. Helix should now display the commands to pick from when :lsp-workspace-command is invoked: