Unnecessary data copies in the implementation

Hi, I found there is a few unnecessary data copies in the function CKKSPackedEncoding::Encode , and which could be eliminated by using the move constructor.
I have created a pull request on GitHub to fix it: Fix unnecessary data copies by correctly using std::move by lscat11 · Pull Request #850 · openfheorg/openfhe-development · GitHub
Could anyone review this PR?

Thanks. We will review it next week.

Created a new issue for this.