Disable approving reviews of external contributors

Specifically I just mean rejecting the non-core reviews who do not include any commentary in their feedback. Generally if a core developer approves without submitting direct feedback, they are saying “yes, this change is okay to merge” and providing the final stamp of approval. However, a new contributor doing so doesn’t accomplish too much. I’ve seen a few newer members of the community submitting the approve button without a word, and this doesn’t really make the process of making the final review any easier for the core devs (which seems to be the whole point of non-core reviews).

What Stefan said sums up the target audience (not every non-core dev review):

To make this less restrictive to contributors, my idea was to require some feedback (even it’s just a generic “Thanks for the contribution” message). If a non-core hit submit without any message, they would receive a message from the bot and the review wouldn’t go through.