fix(which_key): always close on telescope prompt exit

* Add autocmd to make `which_key` window close on prompt exit

Currently `actions.which_key` supports a `close_with_action` option
(default true). When this is set, the `which_key` window will close
after any Telescope action is triggered. This makes sense. However, when
it is false, the `which_key` window remains open even after Telescope
closes. This seems like a bug.

This PR fixes this by setting an autocommand when `close_with_action` is
false to close on prompt exit.

* [docgen] Update doc/telescope.txt
skip-checks: true

* Add autocmd to make `which_key` window close on prompt exit

Currently `actions.which_key` supports a `close_with_action` option
(default true). When this is set, the `which_key` window will close
after any Telescope action is triggered. This makes sense. However, when
it is false, the `which_key` window remains open even after Telescope
closes. This seems like a bug.

This PR fixes this by setting an autocommand when `close_with_action` is
false to close on prompt exit.

---------

Co-authored-by: Github Actions <actions@github>
(cherry picked from commit ae6708a90b)

lua/telescope/actions/init.lua

@@ -1268,20 +1268,27 @@ actions.which_key = function(prompt_bufnr, opts)
     end
   end
 
-  -- only set up autocommand after showing preview completed
+  -- if close_with_action is true, close the which_key window when any action is triggered
+  -- otherwise close the window when the prompt buffer is closed
+  local close_event, close_pattern, close_buffer
   if opts.close_with_action then
-    vim.schedule(function()
-      vim.api.nvim_create_autocmd("User", {
-        pattern = "TelescopeKeymap",
-        once = true,
-        callback = function()
-          pcall(vim.api.nvim_win_close, km_win_id, true)
-          pcall(vim.api.nvim_win_close, km_opts.border.win_id, true)
-          require("telescope.utils").buf_delete(km_buf)
-        end,
-      })
-    end)
+    close_event, close_pattern, close_buffer = "User", "TelescopeKeymap", nil
+  else
+    close_event, close_pattern, close_buffer = "BufWinLeave", nil, prompt_bufnr
   end
+  -- only set up autocommand after showing preview completed
+  vim.schedule(function()
+    vim.api.nvim_create_autocmd(close_event, {
+      pattern = close_pattern,
+      buffer = close_buffer,
+      once = true,
+      callback = function()
+        pcall(vim.api.nvim_win_close, km_win_id, true)
+        pcall(vim.api.nvim_win_close, km_opts.border.win_id, true)
+        require("telescope.utils").buf_delete(km_buf)
+      end,
+    })
+  end)
 end
 
 --- Move from a none fuzzy search to a fuzzy one<br>