[llvm] [RISCV][VLOPT] Add support for 11.14 widening integer mul-add instructions (PR #112219)

[Michael Maitland via llvm-commits]

michaelmaitland wrote:

I have updated the tests to consider the sources.

The tests are generated stacked on https://github.com/llvm/llvm-project/pull/112244. This PR must be rebased on #112244 so it can pass tests.

https://github.com/llvm/llvm-project/pull/112219