Update for GNOME 42 Builder

[mjakeman]

The GNOME 42 release of Builder includes the necessary changes needed to run out-of-the-box. With GNOME 42 around the corner, let's aim to release an initial version that can work with minimal setup needed on the user's end.

In particular:

• Update for latest Builder release
• Use dotnet flatpak runtime if possible (preferable for Silverblue)
• Bundle language server with extension

[mjakeman]

Made some progress towards this on branch update-for-42 however while the plugin is now loaded by stable builder it causes an infinite loop and hangs.