docs(api): document types using LuaCATS types

- Render Lua types in api.txt.

- Added `DictAs(name)` API type which acts the same as `Dict` (no parens)
  when generating the dispatchers, but acts the same as `Dict(name)`
  when generating docs.

- Added `Tuple(...)` API type which is the treated the as `Array` for
  generating the dispatchers, but is used to document richer types.

- Added `Enum(...)` API type to better document enums

- Improve typing of some API functions.

- Improve c_grammar to properly parse API types and replace string pattern
  logic in the parsers.

- Removed all the hardcoded type overrides in gen_eval_files.lua

src/nvim/api/options.c

@@ -308,7 +308,8 @@ Dict nvim_get_all_options_info(Arena *arena, Error *err)
 ///                         Implies {scope} is "local".
 /// @param[out] err Error details, if any
 /// @return         Option Information
-Dict nvim_get_option_info2(String name, Dict(option) *opts, Arena *arena, Error *err)
+DictAs(get_option_info) nvim_get_option_info2(String name, Dict(option) *opts, Arena *arena,
+                                              Error *err)
   FUNC_API_SINCE(11)
 {
   OptIndex opt_idx = 0;