Until gi-docgen is declared stable support either of them.
This effectively means that hand builds and CI builds will use
gi-docgen, but distro builds use gtk-doc-tools.
The kernel interface for force power doesn't support tracking the state
of the device, and so this had to be tracked by fwupd.
Unfortunately due to system and thunderbolt controller firmware behavior
on some systems the thunderbolt controller /still/ didn't return even
when force power state was accurately tracked.
The device model for the uevent related to the device removal being ignored
doesn't really fit into the current fwupd architecture anymore either.
Lastly this is a very legacy feature at this point. Thunderbolt3 controllers
distributed in the last 3 years all operate in 'native' mode meaning that
they will always be powered and use runtime power management.
USB4 controllers won't have a concept of being force powered.
USB4 reimers will have this concept, but the state will be tracked by the
kernel and obfuscated from userspace.
So with all that said, tear out all of the force power related code.