refactor(excmd): pass fargs to Lua for builtin cmds #39528

Problem:
The fallback that tokenizes `eap->arg` by unescaped whitespace (when the
parser doesn't pre-split via `EX_EXPAND` etc.) lives in `nlua_do_ucmd`,
so only user-command callbacks got `eap.fargs`. Builtin commands routed
through `nlua_call_excmd` have to re-parse the args themselves
(e.g. `M.ex_lsp`).

Solution:
- Move the tokenization into `nlua_push_eap` so every Lua handler sees
  `eap.fargs`. Keep only the `EX_NOSPC` override in `nlua_do_ucmd` (the
  `nargs=1`/`?` case which is genuinely user-command-specific).
- Drop the re-parse in `M.ex_lsp`.

runtime/lua/vim/_core/ex_cmd.lua

@@ -174,19 +174,13 @@ local available_subcmds = vim.tbl_keys(actions)
 --- Implements command: `:lsp {subcmd} {name}?`.
 --- @param eap vim._core.ExCmdArgs
 function M.ex_lsp(eap)
-  local fargs = api.nvim_parse_cmd('lsp ' .. eap.args, {}).args
-  if not fargs then
-    return
-  end
-  local subcmd = fargs[1]
+  local subcmd = eap.fargs[1]
   if not vim.list_contains(available_subcmds, subcmd) then
     echo_err(N_('E5800: Invalid :lsp subcommand: %s'):format(subcmd))
     return
   end
 
-  local clients = { unpack(fargs, 2) }
-
-  actions[subcmd](clients)
+  actions[subcmd]({ unpack(eap.fargs, 2) })
 end
 
 --- Completion logic for `:lsp` command

runtime/lua/vim/_core/swapfile.lua

@@ -52,7 +52,7 @@ end
 --- @param items string[] List of swapfile paths.
 function M.select_swap(items)
   vim.ui.select(items, {
-    prompt = N_('Enter number of swap file to use (q or empty cancels):'),
+    prompt = N_('Select a swapfile:'),
     kind = 'swap',
     format_item = format_swap,
   }, function(_, idx)

runtime/lua/vim/_core/tag.lua

@@ -30,7 +30,7 @@ function M.select_tag(eap, extra)
   end
 
   vim.ui.select(items, {
-    prompt = N_('Type number and <Enter> (q or empty cancels):'),
+    prompt = N_('Select a tag:'),
     kind = 'tag',
     format_item = function(m)
       local marker = m.cur and '>' or ' '