Add a StandardDescriptorSetAllocatorCreateInfo

[marc0246]

Fixes an oversight in the original implementation where the number of sets allocated was hard-coded, which would lead to huge memory usage with large descriptor sets (e.g. bindless). The idea is that for bindless, the user would set the set count to 1. They will still need to do manual garbage collection for pools of old descriptor set layouts, and ideally there would be a better solution for bindless specifically, but for now this should do.

Changelog:

### Breaking changes
- `StandardDescriptorSetAllocator` now takes a `StandardDescriptorSetAllocatorCreateInfo` parameter.