Convert applications that use gbulb to use native asyncio on pygobject >= 3.50

[marmarek]

The problem you're addressing (if any)

https://github.com/beeware/gbulb is deprecated as asyncio is supported natively in pygobject 3.50+. And gbulb doesn't work with pygobject 3.50+ anymore (complains about missing GLibEventLoop.running attribute).
Fedora 42 has pygobject 3.50.

The solution you'd like

While fixing gbulb may work as a short term solution (not sure how complex the fix would - it isn't obvious if the running attribute is the only problem), it isn't a long term solution. Migration to native glib support is a better idea long term. But also, for the time being we need to support older pygobject too. The change look to be rather simple: https://github.com/QubesOS/qubes-core-qrexec/pull/191/files, and it should be possible to wrap in some condition based on the pygobject version, or maybe even via try/except ImportError on GlibEventLoopPolicy.

The value to a user and who that user might be

Less dependencies (especially deprecated ones). Necessary for #9807

Completion criteria checklist

The following repositories need to be adjusted:

• core-qrexec (see PR linked above): Use glib's native asyncio integration when available qubes-core-qrexec#208
• desktop-linux-menu: Use glib's native asyncio integration when available qubes-desktop-linux-menu#56
• desktop-linux-manager: Use glib's native asyncio integration when available qubes-desktop-linux-manager#263

[marmarek]

This blocks using F42 for sys-gui: https://openqa.qubes-os.org/tests/135125#step/guivm_startup/24