lsp: Support text edit on inactive buffer (#11843)

Using `vim.lsp.buf.rename()` can result in receiving a TextEdit that
affects a file for which there is no active or loaded buffer.

In that case `api.nvim_buf_get_lines(...)` returned an empty result,
leading to an error.

Closes https://github.com/neovim/neovim/issues/11790

runtime/lua/vim/lsp/util.lua

@@ -88,6 +88,9 @@ function M.apply_text_edits(text_edits, bufnr)
   -- Reverse sort the orders so we can apply them without interfering with
   -- eachother. Also add i as a sort key to mimic a stable sort.
   table.sort(cleaned, edit_sort_key)
+  if not api.nvim_buf_is_loaded(bufnr) then
+    vim.fn.bufload(bufnr)
+  end
   local lines = api.nvim_buf_get_lines(bufnr, start_line, finish_line + 1, false)
   local fix_eol = api.nvim_buf_get_option(bufnr, 'fixeol')
   local set_eol = fix_eol and api.nvim_buf_line_count(bufnr) <= finish_line + 1