[llvm-ir2vec] Creating one directory per library for IRUtils, and MIRUtils (#198170)

Follow up to
https://github.com/llvm/llvm-project/pull/194414#issuecomment-4467455664
.
Made a patch to move IRUtils, and MIRUtils to their own subdirectories

GitOrigin-RevId: b9c7a8e43ac26b0df422cd9a403382f0656785a0
10 files changed