Clean and reorder operation enums.

Four operation enums are removed:
- DETECTION_OUTPUT
- PRIOR_BOX
- SPARSE_TO_DENSE
- EMBEDDING_LOOKUP_SPARSE

Operation enums are reorder into alphabetic order.

Bug: 123253865
Bug: 122744669
Test: NeuralNetworksTest_static
Change-Id: Ie5d2bff6fac061bdca0a99e5b8c8ac05733fac4b