Add Convolution Block Attention

[GLOMQuyet]

What does this PR do?

Fixes # (issue)

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• [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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[innat]

ticket https://github.com/keras-team/keras-cv/issues/324

[GLOMQuyet]

even though it's a match, I haven't seen #324 yet. I will consider making more suggestions

[LukeWood]

Thanks for your enthusiasm @GLOMQuyet !

Apologies for shifting priorities and changes in terms of what we are interested in merging. We've done a lot of work to figure out exactly what our value add to users is, what components we want to offer as APIs, and we don't want to offer as APIs in the last few years. For now, I think closing this PR makes sense and if models need this component we can implement this style layer alongside the model.

This usually has to happen to match exact numerics of architectures anyways. For now lets close, and if theres a super strong user need to fill we can re-open.