Adds a FramebufferCache singletion that operates the same way as UniformSetCache.
Allows creating framebuffers on the fly (and keep them cached if re-requested) such as:
```C++
RID fb = FramebufferCache::get_singleton()->get_cache(texture1,texture2);
```
Clean up and do fixes to hash functions and newly introduced murmur3 hashes in #61934
* Clean up usage of murmur3
* Fixed usages of binary murmur3 on floats (this is invalid)
* Changed DJB2 to use xor (which seems to be better)
* Changed syntax usage for RD::Uniform to create faster with a single RID
* Converted render pass setup to use this in clustered renderer to test.
This is the first step into creating a proper uniform set cache system to simplify large parts of the codebase.
Juan Linietsky
Rémi Verschelde