[AArch64] Consider StreamingSVE in shouldExpandGetActiveLaneMask (#144722)

If StreamingSVE is available, we may be able to lower the intrinsic
to the GET_ACTIVE_LANE_MASK node instead of expanding it.
Also adds the node to addTypeForFixedLengthSVE to ensure we lower
to the SVE instruction when useSVEForFixedLengthVectors is true.

GitOrigin-RevId: 61b99ca51282f8ebe31c0a4c179383883730b8c7
2 files changed