[AArch64][SVE] Add legalization support for i32/i64 vector srem/urem

Implement them on top of sdiv/udiv, similar to what we do for integer
types.

Potential future work: implementing i8/i16 srem/urem, optimizations for
constant divisors, optimizing the mul+sub to mls.

Differential Revision: https://reviews.llvm.org/D81511