[AArch64][SVE] Add integer arithmetic with immediate instructions.

Summary:
Add pattern matching for the following instructions:
- add, sub, subr, sqadd, sqsub, uqadd, uqsub

This patch required complex patterns to match the immediate with optinal left shift.

I re-used the Select function from the other SVE repo to implement the complext pattern.

I plan on doing another patch to also match constant vector of the same immediate.

Reviewers: sdesmalen, huntergr, rengolin, efriedma, c-rhodes, mgudim, kmclaughlin

Subscribers: tschuett, kristof.beyls, hiraditya, rkruppe, psnobl, llvm-commits, amehsan

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71370