[AArch64][SVE2] Asm: support SVE2 Accumulate Group

Summary:
Patch adds support for the following instructions:

SVE2 bitwise shift and insert:
    * SRI, SLI

SVE2 bitwise shift right and accumulate:
    * SSRA, USRA, SRSRA, URSRA

SVE2 complex integer add:
    * CADD, SQCADD

SVE2 integer absolute difference and accumulate:
    * SABA, UABA

SVE2 integer absolute difference and accumulate long:
    * SABALB, SABALT, UABALB, UABALT

SVE2 integer add/subtract long with carry:
    * ADCLB, ADCLT, SBCLB, SBCLT

The specification can be found here:
https://developer.arm.com/docs/ddi0602/latest

Reviewed By: SjoerdMeijer

Differential Revision: https://reviews.llvm.org/D62204

llvm-svn: 361622