License Keys: Prefix with POLAR

[birkjernstrom]

Feature request: Polar license keys to be a part of GitHub Secret Scanning partnership.

We're working on the above for our access tokens. They are prefixed with polar. By prefixing our license keys with polar too we can get coverage for Polar license keys too. However, this should likely be an opt-in in the benefit settings to use the polar prefix to get this advantage, or explicitly skip it in the event it's likely not helpful for their use case and polar is not a desired prefix.