Recommit "[AArch64][SVE] Add permutation and selection intrinsics"

Recommit 23c28c40 (reverted in
dcb48f50) with a fix for an assert
"Request for a fixed size on a scalable object" being triggered in
`LowerSVEIntrinsicEXT`. The fix is to call `getKnownMinSize` on the
TypeSize object.