BroadPhaseSystem & GridFixtureSystem clean up

[TheShuEd]

file-scoping,
EntityQuery dependency injection
makes dependencies readonly

Again, I'm not changing the underlying logic; I'm just removing outdated style and updating the code to meet modern standards

[TheShuEd]

GridSplitEvent as a result of this change, it ended up inside the system namespace (which is correct, in theory).

But the content, of course, doesn't know this.

I don’t quite understand exactly how we should handle situations like this:

Changing the namespace in the content will also cause errors without changing the engine, and changing the engine will cause errors in the content. I can certainly create a PR with a fix for the content, but should these changes be merged simultaneously? That doesn’t feel right. How is this handled?

[slarticodefast]

I can certainly create a PR with a fix for the content, but should these changes be merged simultaneously? That doesn’t feel right. How is this handled?

Make a content PR that fixes the namespace import and write requires https://github.com/space-wizards/RobustToolbox/pull/6565 into the Pr description so that it uses this engine branch so that the tests can pass. It will then be merged along with the next engine release.