Rewrite the Submodule Update Bot

The Submodule Update Bot has been having a number of unexplained issues in recent months. These include picking incorrect shas mid-round and failing to use the correct shas in the qt5 update. Further, the bot is incapable of performing updates to tqtc/* repos, as it is very inflexible about repo prefixes.

Modifying the bot is not practical, as it is written in Go and would require a lot of hacking to diagnose current issues, and update the bot with support for tqtc/* repos. Rewriting the bot provides the opportunity to:

• Use Python. Speed is not important in this bot, and Python is much friendlier to modify than Go in the event the bot needs to be updated in the future.
• Add new features like the ability to rewind a round when a problem requires a fix in trunk module to fix a leaf module, but does not require restarting at qtbase.
• Intelligently select repos to update and use the correct prefix.
• Provide the capability to update repos outside of the qt/qt5 module set, syncing them with current qt5 shas, or performing an update round from scratch but including the non-qt5 module(s).
• Sweep in changes to a submodule update when the bot user account is added as a reviewer on a change, and that change is approved for integration (Code-review: +2).
• Update yocto/meta-qt6 with submodule shas as part of a normal round.
• Remove no longer required submodules from qt5, or remove a dependency from one or modules.