fix(definition): import submodule as alias

[aaron-ang]

Summary

Resolve goto-definitions for submodule imports as aliases. Previously, only hover information was available.
For example,

from torch.nn import (
    attention as attention,
    functional as functional,
    init as init,
    modules as modules,
    parallel as parallel,
    parameter as parameter,
    utils as utils,
)

Test Plan

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[stroxler]

Thanks for the PR! Looks reasonable to me, I'll aim to get a second review and merge

[meta-codesync]

@stroxler has imported this pull request. If you are a Meta employee, you can view this in D90599710.

[yangdanny97]

Review automatically exported from Phabricator review in Meta.

[meta-codesync]

@stroxler merged this pull request in a9c9a5f.