[RISCV][VLOPT] Add separate tests for getOperandInfo. NFC (#116170)

This adds separate tests for getOperandInfo to try and get better
coverage over all the possible operands.

It's done in MIR as it makes checking incompatible EEWs and EMULs
easier, which is difficult (but not impossible) to do in LLVM IR.

It tests each instruction "format", e.g. vop.vv/vwop.vv/vwop.wv etc.,
and for each format it tests the individual operands.

For each operand it tests when the EEW and EMUL match, when the EEW
doesn't match, and when the EMUL doesn't match.

Author: lukel97