backport: feat(api): rename buffer to buf (#38899)

feat(api): rename buffer to buf

Problem:
`:help dev-name-common` states that "buf" should be used instead of
"buffer" but there are cases where buffer is mentioned in the lua API.

Solution:
- Rename occurrences of "buffer" to "buf" for consistency with the
  documentation.
- Support (but deprecate) "buffer" for backwards compatibility.

Co-authored-by: Jordan <46637683+JordanllHarper@users.noreply.github.com>

runtime/ftplugin/query.lua

@@ -22,7 +22,7 @@ local query_lint_on = vim.g.query_lint_on or {}
 if not vim.b.disable_query_linter and #query_lint_on > 0 then
   vim.api.nvim_create_autocmd(query_lint_on, {
     group = vim.api.nvim_create_augroup('nvim.querylint', { clear = false }),
-    buffer = buf,
+    buf = buf,
     callback = function()
       vim.treesitter.query.lint(buf)
     end,