[mlir][transform] Introduce transform.sequence op

Sequence is an important transform combination primitive that just indicates
transform ops being applied in a row. The simplest version requires fails
immediately if any transformation in the sequence fails. Introducing this
operation allows one to start placing transform IR within other IR.

Depends On D123135

Reviewed By: Mogball, rriddle

Differential Revision: https://reviews.llvm.org/D123664