[Feature]: add ability to assign reviewer of PR

[kellijohnson-NOAA]

Is your feature request related to a problem? Please describe.

We use the style and code workflow for R code in the NOAA-FIMS/FIMS repo to style the R code but it would be nice if we were able to automatically assign a reviewer of the opened pull request from the reusable workflow within our workflow file.

Describe the solution you would like.

I would like it if we could pass the following to the reviewer argument of peter-evans/create-pull-request@v8

${{ github.event.pull_request.user.login }}

that way whoever opened the original pull request would be assigned to review the pull request that is now open to their feature branch.
I was able to do this to our clang formatting workflow in PR #1069 but that is because we do not use a reuseable workflow for clang.

Describe alternatives you have considered

We could not use this reusable workflow for FIMS and just have our own workflow. We could manually assign the reviewer. We could always assign a certain person to review the PR but that doesn't allow people to learn from their own coding errors.

Additional context

No response

[k-doering-NOAA]

@kellijohnson-NOAA this is a great idea and seems straightforward.

If you feel comfortable doing the work yourself and opening a PR, please feel free and I can review it. Otherwise, I will add this into the planning for the next release of ghactions4r (but we can make it available as soon as the work is done)