Add CODEOWNERS for the primitives submodule (#7810)
Add CODEOWNERS for the primitives submodule (#7810)

The primitives submodule was recently added in the #7723. As the primary
authors of this new submodule were @ikkoham and @t-imamichi and they are
the most familiar with its operation and how it was written this commit
adds both of them as codeowners for this submodule. As codeowners they
have merge permission on the submodule as well as a formal
responsibility to review and maintain it.

Co-authored-by: mergify[bot] <b09a6ee808b67e98a221404e7aaa52e0398a4954@users.noreply.github.com>
QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py