Move VectorOps to Tablegen - (almost) NFC

This CL moves VectorOps to Tablegen and cleans up the implementation.

This is almost NFC but 2 changes occur:
  1. an interface change occurs in the padding value specification in vector_transfer_read:
     the value becomes non-optional. As a shortcut we currently use %f0 for all paddings.
     This should become an OpInterface for vectorization in the future.
  2. the return type of vector.type_cast is trivial and simplified to `memref<vector<...>>`

Relevant roundtrip and invalid tests that used to sit in core are moved to the vector dialect.

The op documentation is moved to the .td file.

PiperOrigin-RevId: 280430869