Finish up Image refactor work

[emilk]

We should start with the struct ImageFormat component refactor (TODO: add link) and hence int-enum

• [x] Update MaxImageDimensionSubscriber
• [ ] Log warnings in image constructors if the buffer has the wrong length in C++ and Python
• [x] Move .compress back to Image.
• [x] Remove tensor_to_gpu
• [x] Rename ChannelDataType to ChannelDatatype for consistency
• [x] Rust: create Image constructors for image crate
• [x] Remove ImageChromaDownsampled
• [x] https://github.com/rerun-io/rerun/pull/7087
• [x] https://github.com/rerun-io/rerun/pull/7088
• [ ] Rename TensorElement?
• [ ] Document what row-major means for C++/Rust image constructors
• [x] Document what borrowing means for C++ constructors

[emilk]

I'll start tackling some of these renamings