Allow specifying view target format in cameras

[beicause]

Objective

Closes #13011. Supersedes #13146.

Solution

This adds a CameraMainTextureFormat componet which specifies view target format for hdr and sdr.
Different from #13011:

• Use TextureFormat instead of a new ViewTargetFormat struct, only a subset of texture is allowed and hardcoded, using unsupported format will panic.
• Need to specify both hdr and sdr format, retain the hdr field to determine whether to use the hdr format. Technically, hdr formats are not necessarily unclamped, as you can use unorm format textures and multiply by a factor to scale the range and achieve overbright areas. For example, Godot mobile renderer uses the RGB10A2 format with 2x luminance multiplier to achieve bloom. Although this approach is more complex, has lower precision and Bevy has not implemented it.

Usually, you should use Rgba8UnormSrgb for sdr and Rgba16Float/Rg11b10Float for hdr. On mobile devices It's better to use 32-bit formats due to their limited bandwidth, and 32-bit formats support framebuffer compression. High-end mobile devices may support 64-bit framebuffer compression.

Testing

I changed the bloom_3d example to use Rg11b10Ufloat, it should work in many cases. It won't work with some effects using compute shaders if the compute shaders hardcode the view target input/output as rgba16f.

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[tychedelia]

I'm extremely in favor of this, but think we may want to consider a bit more how to just make the internal/intermediate render texture more fully configurable. I'm happy to approve something like this as an incremental step but may have some nits about naming, etc.

[tychedelia]

See also #19704