Missing RBI declarations for APIs made by `gobject-introspection`

TL;DR: tapioca dsl misses modules created for GObject interfaces, and maybe other types, too.

Cause

gobject-introspection is a gem brigding to GObject APIs.

For example, GObject interfaces get modelled via Ruby Modules, created here, and set via const_set here. Every such interface will have its const_source_location point to gobject-introspection/lib/gobject-introspection/loader.rb#L618.

When other gems (like gio2) import GObject interfaces, their const_source_location will always point to gobject-introspection/lib/gobject-introspection/loader.rb#L618. Since this location is outside the gem (and in gobject-introspection), Tapioca will skip those module, because it's not defined_in_gem?:

https://github.com/Shopify/tapioca/blob/b8161b8dc60f3208261579bcb3aeed017e60483b/lib/tapioca/gem/pipeline.rb#L449-L455

As a result, the generated gio2.rbi will be missing some interface declaration. It will still include lines that rely on them, leading to type errors.

Start in lib/tapioca/gem/pipeline.rb around lines 449-455 and reproduce RBI generation for the gio2 gem. Trace how const_source_location and defined_in_gem? cause GObject interface modules to be skipped; done means the generated gio2.rbi includes the missing interface declarations without producing type errors from its include lines.