Introduce tensor.insert op to Tensor dialect.

Add `tensor.insert` op to make `tensor.extract`/`tensor.insert` work in pairs
for `scalar` domain. Like `subtensor`/`subtensor_insert` work in pairs in
`tensor` domain, and `vector.transfer_read`/`vector.transfer_write` work in
pairs in `vector` domain.

Reviewed By: silvas

Differential Revision: https://reviews.llvm.org/D104139