Make a little overlay to show diagnostics

[hukasu]

Objective

LogDiagnosticsPlugin prints the values on the DiagnosticStore to the console, which is spam-y, create an alternative that is visual

Solution

Create RenderAssetsOverlayPlugin to create an UI that presents the data for the MaterialAllocatorDiagnosticPlugin::<StandardMaterial> and MeshAllocatorDiagnosticPlugin on a draggable and collapsable window

Testing

Enabled it on the many_foxes example

Showcase

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[alice-i-cecile]

Part of me thinks that we should use the Name component instead, but I won't block on that.

[IceSentry]

I would also note that the log diagnostic plugin can measurably impact performance every time it logs things to the console so having something that doesn't need to do IO is much better to report performance metrics.

[alice-i-cecile]

@hukasu feel free to resolve conversations when the feedback has been addressed, so we can quickly tell the status of work items when reviewing :)

[alice-i-cecile]

We don't have a particularly clear story about what Name should / should not be used for right now. Let's leave it out for now, and move forward with this.

[janis-bhm]

I have a few non-blocking thoughts:
DiagnosticOverlays with missing DiagnosticOverlayItems show up as "Missing"; maybe it makes sense to hide these entirely? It would mean that removing diagnostics from the engine automatically declutters the diagnostics overlay.

I've also noticed that there is a bit of overlap with the FpsOverlay: notably the Z indices are wildly different even though the intent seems very similar to me, and I think that time graphs like the FpsOverlay has for frame times would be a cool addition to this overlay in the future as well.

Otherwise I think this is a great addition which makes it easy to look at diagnostics at a glance vs scrolling through terminal output.