[llvm] [NFC][IR2Vec][MIR2Vec] llvm-ir2vec refactor - move Tool class implementations into a separate utils file (PR #174133)

[Nikita Popov via llvm-commits]

nikic wrote:

Please also familiarize yourself with our [AI policy](https://llvm.org/docs//AIToolPolicy.html), in particular the requirement to disclose AI use and the recommendation to not use AI for pull request descriptions.

https://github.com/llvm/llvm-project/pull/174133