[llvm] [IR2Vec] Add out-of-place arithmetic operators to Embedding class (PR #145118)

[S. VenkataKeerthy via llvm-commits]

svkeerthy wrote:

### Merge activity

* **Jul 1, 7:09 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/145118).


https://github.com/llvm/llvm-project/pull/145118