Add VM option for AArch64 to optionally select SVE feature
Arm SVE  and SVE2  are optional extentions to Arm architecture. VM needs to detect SVE version in running hardware and generate code for non-SVE, SVE1 and SVE2 to get best performance. And we can also enable or disable SVE based on different applications or use cases.
 https://developer.arm.com/architectures/cpu-architecture/a-profile/docs/arm-architecture-reference-manual-supplement-armv8-a  https://developer.arm.com/tools-and-software/server-and-hpc/compile/arm-instruction-emulator/resources/tutorials/sve/sve-vs-sve2/introduction-to-sve2
We add a VM option UseSVE to control which SVE version is going to be used or not using SVE at all. This is similar to x86 UseAVX option.
We add a new VM option, UseSVE, which is an integer with the following valid values:
0: Do not use SVE, even when the hardware supports SVE.
1: Use SVE version 1
2: Use SVE version 2