[lldb][AArch64] Add Scalable Matrix Extension option to QEMU launch script

The Scalable Matrix Extension (SME) does not require extra options
beyond setting the cpu to "max".

https://qemu-project.gitlab.io/qemu/system/arm/cpu-features.html#sme-cpu-property-examples

SME depends on SVE, so that will be enabled too even if you don't ask
for it by name.

--sve --sme -> SVE and SME
--sme       -> SVE and SME
--sve       -> Only SVE

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D152519