[ARM] Refactor lower to S[LR]I optimization

Summary:
The optimization has been refactored to fix certain bugs and
limitations. The condition for lowering to S[LR]I has been changed
to reflect the manual pseudocode description of SLI and SRI operation.
The optimization can now handle more cases of operand type and order.

Subscribers: kristof.beyls, hiraditya, danielkiss, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79233