Fix Apple arm64 SIMD12(SIMD16) passing.

[sandreenko]

Fixes #49453, and closing #49110 (was fixed by JanV's changes).

[sandreenko]

The tree looks like:

N004 (  3,  2) [000046] -------N----        t46 =    LCL_VAR   simd12<System.Numerics.Vector3> V02 arg2
                                                  /--*  t46    simd12
               [000190] ------------              *  PUTARG_STK [+0x00] void   (12 stackByteSize), (0 byteOffset)

when on other platforms PUTARG_STK is 16 bytes.

Note that we already had special logic for 12 arguments passed as SIMD12 in the struct case but it was missed in non-struct case.

runtime/src/coreclr/jit/codegenarmarch.cpp

Lines 1036 to 1040 in a943e37

	// For a 12-byte structSize we will we will generate two load instructions
	// ldr x2, [x0]
	// ldr w3, [x0, #8]
	// str x2, [sp, #16]
	// str w3, [sp, #24]

[sandreenko]

PTAL @BruceForstall @dotnet/jit-contrib , cc @janvorli

[sandreenko]

Another note: we can't reuse struct case because structs are coming in memory. We currently don't treat m_size==12 as enregistrable type.

runtime/src/coreclr/jit/layout.h

Lines 135 to 138 in 48b3d37

	// TODO: check TYP_SIMD12 profitability,
	// it will need additional support in `BuildStoreLoc`.
	case 16:
	return TYP_SIMD16;