Make module suggestion avaliable on built-in modules

Feature or enhancement

Proposal:

Add BuiltinImporter.discover to make it:

class BuiltinImporter:
    @staticmethod
    def discover(spec=None):
        if spec is not None: # assume that built-in modules have no submodule
            return
        yield from sys.builtin_module_names

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-146421

从 issue 中描述的 BuiltinImporter.discover 入口开始，检查内置模块发现的处理方式。完成标准是：无需将子模块视为受支持项，即可发现内置模块名称；开始前请检查链接的 PR gh-146421，因为相关工作可能已经在进行中。