refactor(class): change type returned by lib.class

Return a new type named after the class, rather than OxClass.
We still can't use class generics (i.e. OxClass<`T`>), so classes
still need to be declared (e.g. ---@class Person : OxClass).

Also removed the experimental warning.

imports/class/shared.lua

@@ -1,10 +1,6 @@
 ---@diagnostic disable: invisible
 local getinfo = debug.getinfo
 
-if not getinfo(1, 'S').source:match('^@@ox_lib') then
-    lib.print.warn('ox_lib\'s class module is experimental and may break without warning.')
-end
-
 ---Ensure the given argument or property has a valid type, otherwise throwing an error.
 ---@param id number | string
 ---@param var any
@@ -132,8 +128,10 @@ end
 
 ---Creates a new class.
 ---@generic S : OxClass
----@param name string
+---@generic T : string
+---@param name `T`
 ---@param super? S
+---@return `T`
 function lib.class(name, super)
     assertType(1, name, 'string')