fix(lsp): enable() does not activate inlay hints on open buffers #28629

Problem:
inlay_hint `enable(<no args>)` does not activate inlay hints on open
buffers. If a buffer does not have a corresponding `bufstate` in
`bufstates`, then `enable` all buffers will not take effect on it.

Solution:
Make the effective range determined by the loaded buffers.

Fix #28624

runtime/lua/vim/lsp/inlay_hint.lua

@@ -429,7 +429,7 @@ function M.enable(enable, filter)
 
  if filter.bufnr == nil then
  globalstate.enabled = enable
- for bufnr, _ in pairs(bufstates) do
+ for _, bufnr in ipairs(api.nvim_list_bufs()) do
  if api.nvim_buf_is_loaded(bufnr) then
  if enable == false then
  _disable(bufnr)