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/deprecated.c

@@ -603,7 +603,7 @@ static int64_t convert_index(int64_t index)
 /// @param          name Option name
 /// @param[out] err Error details, if any
 /// @return         Option Information
-Dict nvim_get_option_info(String name, Arena *arena, Error *err)
+DictAs(get_option_info) nvim_get_option_info(String name, Arena *arena, Error *err)
   FUNC_API_SINCE(7)
   FUNC_API_DEPRECATED_SINCE(11)
 {