[AArch64] Added tests for inserting scalar result of uaddlv neon instrinsic function into a vector

Inserting scalar result of 'uaddlv' neon intrinsic function to a destination vector currently makes use of the integer unit. Subsequent patches will eliminate the redundant use of the integer registers in a more generic way that will include this special case. This is an initial set of tests for this functionality.

Differential Revision: https://reviews.llvm.org/D143038