Fully enable HDR2D when the setting is changed

[clayjohn]

When I added HDR2D, I ended up making it force a restart when the project setting was changed because the editor would look wrong until restart. There was no technical reason for it, I just couldn't figure out how to change the setting for the editor's root Viewport.

This PR ensures that the setting gets changed for both the SubViewports (2D and 3D which already worked) and the editor root. So now there is no need to restart.

This issue came up today in the rendering meeting as it makes proper HDR a little more awkward CC @DarkKilauea

This issue was also noted by @Calinou in the original PR #80215 (review)

[Repiteo]

Thanks!

[Calinou]

Tested locally, it works as expected in all rendering methods.

PS: Something I noticed is that when you toggle HDR 2D in Compatibility (where it has no effect), the clear color will become very slightly darker:

With HDR 2D disabled, it's #4d4d4d while it's #4c4c4c with HDR 2D enabled. With Mobile, the opposite phenomenon happens: it's #4c4c4c with HDR 2D disabled and #4d4d4d with HDR2D enabled. Forward+ has #4c4c4c regardless. The intended color is #4d4d4d as the default clear color is (77, 77, 77).

[bonjorno7]

Does this also fix the editor colors looking different?
The reason I don't use HDR 2D at the moment is because it makes everything in the editor more contrasting, and the 2D grid much brighter, which is unpleasant to look at.

[clayjohn]

Does this also fix the editor colors looking different? The reason I don't use HDR 2D at the moment is because it makes everything in the editor more contrasting, and the 2D grid much brighter, which is unpleasant to look at.

I'm not sure what you mean. Previously when enabling HDR2D colors in the 2D and 3D viewport would look really dark until a restart. This fixes that problem.

When enabling HDR2D the color of transparent objects will change in comparison to when it's disabled. Which is the expected behaviour. Non transparent objects should look the same though

[Calinou]

The reason I don't use HDR 2D at the moment is because it makes everything in the editor more contrasting, and the 2D grid much brighter, which is unpleasant to look at.

This is being tracked at #80912.