feat(lsp): vim.lsp.get_configs() #37237

Problem:
No way to iterate configs. Users need to reach
for `vim.lsp.config._configs`, an internal interface.

Solution:
Provide vim.lsp.get_configs().
Also indirectly improves :lsp enable/disable completion
by discarding invalid configs from completion.

runtime/lua/vim/_core/ex_cmd.lua

@@ -19,45 +19,22 @@ local function get_client_names()
     :totable()
 end
 
---- @return string[]
-local function get_config_names()
-  local config_names = vim
-    .iter(api.nvim_get_runtime_file('lsp/*.lua', true))
-    --- @param path string
-    :map(function(path)
-      local file_name = path:match('[^/]*.lua$')
-      return file_name:sub(0, #file_name - 4)
-    end)
-    :totable()
-
-  --- @diagnostic disable-next-line
-  vim.list_extend(config_names, vim.tbl_keys(lsp.config._configs))
-
-  return vim
-    .iter(config_names)
-    :unique()
-    --- @param name string
-    :filter(function(name)
-      return name ~= '*'
-    end)
-    :totable()
-end
-
---- @param filter fun(string):boolean
+--- @param filter vim.lsp.get_configs.Filter
 --- @return fun():string[]
 local function filtered_config_names(filter)
   return function()
-    return vim.iter(get_config_names()):filter(filter):totable()
+    return vim
+      .iter(lsp.get_configs(filter))
+      :map(function(config)
+        return config.name
+      end)
+      :totable()
   end
 end
 
 local complete_args = {
-  enable = filtered_config_names(function(name)
-    return not lsp.is_enabled(name)
-  end),
-  disable = filtered_config_names(function(name)
-    return lsp.is_enabled(name)
-  end),
+  enable = filtered_config_names { enabled = false },
+  disable = filtered_config_names { enabled = true },
   restart = get_client_names,
   stop = get_client_names,
 }
@@ -79,17 +56,10 @@ local function ex_lsp_enable(config_names)
   -- Default to enabling all clients matching the filetype of the current buffer.
   if #config_names == 0 then
     local filetype = vim.bo.filetype
-    for _, name in ipairs(get_config_names()) do
-      local success, result = pcall(function()
-        return lsp.config[name]
-      end)
-      if success then
-        local filetypes = result.filetypes
-        if filetypes == nil or vim.list_contains(filetypes, filetype) then
-          table.insert(config_names, name)
-        end
-      else
-        echo_err(result --[[@as string]])
+    for _, config in ipairs(lsp.get_configs()) do
+      local filetypes = config.filetypes
+      if filetypes == nil or vim.list_contains(filetypes, filetype) then
+        table.insert(config_names, config.name)
       end
     end
     if #config_names == 0 then