Rename 2D NoiseTexture to NoiseTexture2D

[aaronfranke]

This rename would be helpful to have done before implementing godotengine/godot-proposals#4946

However, I think this stands on its own. Since it inherits Texture2D it makes sense to have the name end in Texture2D, so I'm opening a PR just for this. I briefly discussed this on RocketChat.

[clayjohn]

Discussed on Rocketchat, we should merge this before beta so that we have room to implement a NoiseTexture3D in the future without breaking compatibility.

[akien-mga]

What about all the other *Texture classes though, like AnimatedTexture or CanvasTexture?

[aaronfranke]

@akien-mga I don't know about each case, but in general that makes sense and I would be in favor of renaming some of those too. For this PR, in addition to the Texture2D inheritance, I am focused on this case because 3D noise is known to be a desired feature so if those cases deserve a rename then this case definitely does with this additional reason in mind.

[akien-mga]

Discussed it with @reduz who seems to be fine with the change:

<Akien> @reduz Thoughts on #64864 ? My main doubt is that it adds more inconsistency in the naming of our texture classes.
Currently, most classes inheriting Texture2D don't use the 2D suffix:
[img of the classes inheriting Texture2D]
<reduz> @Akien it would make sense if we think a NoiseTexture3D makes sense
which may do
the others are clearly 2D only
<Akien> Yeah this PR is in support of a proposal to add NoiseTexture3D
My doubt is whether we'll ever want to also add AnimatedTexture3D or something like that.
<reduz> probably not, and that reminds me that i need to remove ProxyTexture
its not so useful now and its not so efficient in Vulkan 

[akien-mga]

Thanks!