Move action inputs from workflow file to configuration file

[joao-paulo-parity]

Problem: GitHub does not provide a $WORKFLOW_PATH for us to enforce that the workflow is triggered from a protected location (related to built-in checks. According to https://docs.github.com/en/actions/learn-github-actions/environment-variables#default-environment-variables:

If the workflow file doesn't specify a name, the value of this variable is the full path of the workflow file in the repository.

However:

1. We do want to specify a readable name for the workflow since its commit status is created from this name
2. It is wasteful to fetch both the configuration and workflow files, for the sake of protecting the latter, when we can simply get most inputs from the configuration file, thus only needing one request
3. Even if the workflow's location can be protected, it's not easy to guarantee that there won't be multiple workflows using this same action in the same repository

Solution: since we're using a configuration file, the action inputs defined in https://github.com/paritytech/pr-custom-review/blob/master/action.yml, except the token, can be moved to that instead of passing them through the workflow's job inputs. Doing so would allow us to protect the inputs without having to put locks above team names.

[joao-paulo-parity]

The relevant GitHub ticket for the desired, but not yet implemented WORKFLOW_PATH, is community/community#4188