feat(ui): use vim.ui.select for :tselect, z= #39478

Problem:
`:tselect` and `z=` (spell suggest) have their own bespoke select menus.

Solution:
- Delegate to `vim.ui.select` instead.
- Bonus:
  - `:tselect` gains mouse support. `print_tag_list` didn't suport mouseclick.

This causes some minor regressions, which are not blockers:

- `z=` no longer draws the list right-left if 'rightleft' is set.
  - TODO: can/should `vim.ui.select` / `vim.fn.inputlist()` handle that?
- `:tselect`
  - No "column" headings (`# pri kind tag file`).
  - No highlighting: (HLF_T: tag name, HLF_D: file, HLF_CM: extra fields).
  - TODO: can `vim.ui.select()` support highlighted chunks (`[[text, hl_id], ...]`) ?

fix https://github.com/neovim/neovim/issues/25814
fix https://github.com/neovim/neovim/issues/31987

runtime/lua/vim/ui.lua

@@ -26,11 +26,11 @@ local M = vim._defer_require('vim.ui', {
 ---@field kind? string
 
 --- Prompts the user to pick from a list of items, allowing arbitrary (potentially asynchronous)
---- work until `on_choice`.
+--- work until `on_choice`. This is the standard "picker" interface, used by |z=|, |:tselect|, etc.
 ---
---- Plugins may override `vim.ui.select` to provide a custom "picker" interface; they are expected
---- to call the `format_item` and `preview_item` handlers (if any) provided by the caller. They may
---- also use the `kind` hint (if provided by the caller) to decide how to handle some items.
+--- Plugins may override `vim.ui.select` to provide a custom picker; they are expected to call the
+--- `format_item` and `preview_item` handlers (if any) provided by the caller. They may also use the
+--- `kind` hint (if provided by the caller) to decide how to handle some items.
 ---
 --- Note: the default `vim.ui.select` currently doesn't support preview.
 ---