[HW] Introduce high level array operations

Currently there is no high-level abstraction for performing vector/comprehensive operations over arrays. Potentially it would be beneficial to capture array structure in terms of verilog quality or simulation speed up(lowing into SIMD operations). Perhaps it's necessary to introduce a new dialect, but here is the list of operations in my mind:

* comprehensive ops: hw.array.map, hw.array.reduce, hw.array.fold
* vector operations: hw.arrray.{xor, or, and, add, sub, ...}.

Start by determining how CIRCT represents arrays and whether these operations belong in a new dialect or an existing one. Use the proposed map, reduce, fold, and vector operations as the scope to resolve; the work is done when the design and operation set are specified with appropriate verification and coverage.

Written by the indexing model from the issue text.