[AArch64] Add check that prologue insertion doesn't clobber live regs. (#71826)

This patch extends AArch64FrameLowering::emitProglogue to check if the
inserted prologue clobbers live registers.

It updates `llvm/test/CodeGen/AArch64/framelayout-scavengingslot.mir`
with an extra load to make x9 live before the store, preserving the
original test.

It uses the original
`llvm/test/CodeGen/AArch64/framelayout-scavengingslot.mir` as
`llvm/test/CodeGen/AArch64/emit-prologue-clobber-verification.mir`,
because there x9 is marked as live on entry, but used as scratch reg as
it is not callee saved.

The new assertion catches a mis-compile in
`store-swift-async-context-clobber-live-reg.ll` on
https://github.com/apple/llvm-project/tree/next