WebXRManager: Mark XR rendertarget as needing a resolve for depth or stencil.

[cabanier]

This change will indicate if the depth and stencil buffer should be preserved and passed to the XR Compositor.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	336.51 78.38	336.65 78.39	+136 B +13 B
WebGPU	521.78 144.83	521.96 144.85	+180 B +23 B
WebGPU Nodes	521.25 144.72	521.43 144.75	+180 B +24 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	465.51 112.23	465.64 112.24	+136 B +13 B
WebGPU	592.15 160.44	592.33 160.47	+180 B +26 B
WebGPU Nodes	547.28 149.88	547.47 149.91	+180 B +26 B

[Mugen87]

The WebGL 2 (and WebGPU) backend of WebGPURenderer does not yet honor the resolve* flags. That needs to be fixed with a different PR.

[cabanier]

yes. The XR part is also using ignoreDepthValues to not pass the depth buffer and use that as a signal to ignore it in the renderer. That should also be updated.