feat(lsp)!: vim.lsp.inlay_hint.get(), enable(), is_enabled() #25512

refactor!: `vim.lsp.inlay_hint()` -> `vim.lsp.inlay_hint.enable()`

Problem:
The LSP specification allows inlay hints to include tooltips, clickable
label parts, and code actions; but Neovim provides no API to query for
these.

Solution:
Add minimal viable extension point from which plugins can query for
inlay hints in a range, in order to build functionality on top of.

Possible Next Steps
---

- Add `virt_text_idx` field to `vim.fn.getmousepos()` return value, for
  usage in mappings of `<LeftMouse>`, `<C-LeftMouse>`, etc

runtime/lua/vim/lsp.lua

@@ -24,6 +24,7 @@ local lsp = {
   buf = require('vim.lsp.buf'),
   diagnostic = require('vim.lsp.diagnostic'),
   codelens = require('vim.lsp.codelens'),
+  inlay_hint = require('vim.lsp.inlay_hint'),
   semantic_tokens = semantic_tokens,
   util = util,
 
@@ -2439,13 +2440,6 @@ function lsp.with(handler, override_config)
   end
 end
 
---- Enable/disable/toggle inlay hints for a buffer
----@param bufnr (integer) Buffer handle, or 0 for current
----@param enable (boolean|nil) true/false to enable/disable, nil to toggle
-function lsp.inlay_hint(bufnr, enable)
-  return require('vim.lsp.inlay_hint')(bufnr, enable)
-end
-
 --- Helper function to use when implementing a handler.
 --- This will check that all of the keys in the user configuration
 --- are valid keys and make sense to include for this handler.