Add dependency tracking for blueprints

[lL1l1]

Issue

Reloading merge blueprints requires a full restart of the session because:

• The engine does unexpected things with nil fields in blueprints, which merge blueprints have plenty of.
• The load order from initial blueprint loading may have an impact if multiple mods merge into the same fields in the same bp. Reloading blueprints only reloads the changed blueprint, so load order is ignored completely.
• A variety of lua code edits blueprint values based on other blueprint values. If a merge blueprint is reloaded, the nil case is used instead of whatever it should be when loading the full stack of edits. Some examples are mesh blueprints being reassigned and target check intervals being changed.

Check out the commit where the debug blueprints are added to see more details.

Description of the proposed changes

On the initial loading, track which file changed what blueprint id, and when reloading a file, run all the files that changed the bp in the appropriate order.
I think this is the only way to solve the given issues as there is unfixable engine behavior involved, using __blueprints does not respect load order (and allows for recursion), and fixing all the Lua would involve far more complexity.

Testing done on the proposed changes

Check out the commit before the debug blueprints are removed.
Reloading the debug blueprints does what is expected of load order and the unit functions correctly ingame. None of the issues commented in the debug blueprints occur.

Additional Context

I was running into these issues while writing the SACU rebalance mod.

Checklist

• Changes are annotated, including comments where useful
• Changes are documented in the changelog for the next game version