[mips][msa] Added tests for and.v, bmnz.v, bmz.v, bsel.v, nor.v, or.v, xor.v when non-byte vectors are used.

Note that all of these tests use ld.b and st.b for the loads and stores
regardless of the data size. This is because the definition of bitcast is
equivalent to a store/load sequence and DAG combiner accordingly folds bitcasts
to/from v16i8 into the load/store nodes to product load/store nodes with
type v16i8.