Improve code and clarify parameters to ABI_Push/PopRegistersAndAdjustStack.

- Factor common work into a helper function.
- Replace confusingly named "noProlog" with "rsp_alignment".  Now that
x86 is not supported, we can just specify it explicitly as 8 for
clarity.
- Add the option to include more frame size, which I'll need later.
- Revert a change by magumagu in March which replaced MOVAPD with MOVUPD
on account of 32-bit Windows, since it's no longer supported.  True,
apparently recent processors don't execute the former any faster if the
pointer is, in fact, aligned, but there's no point using MOVUPD for
something that's guaranteed to be aligned...
Remove the inaccurately named ABI_PushAllCalleeSavedRegsAndAdjustStack (it didn't preserve FPRs!) and replace with ABI_PushRegistersAndAdjustStack.

To avoid FPRs being pushed unnecessarily, I checked the uses: DSPEmitter
doesn't use FPRs, and VertexLoader doesn't use anything but RAX, so I
specified the register list accordingly.  The regular JIT, however, does
use FPRs, and as far as I can tell, it was incorrect not to save them in
the outer routine.  Since the dispatcher loop is only exited when
pausing or stopping, this should have no noticeable performance impact.
Remove ABI_AlignStack/ABI_RestoreStack and the noProlog option to ABI_CallFunctionRR.

The latter being true was the only case where the former would do
anything, and it was never true.  They became obsolete with x86's
removal.