Add more flexible permission set.

This MR creates a flexible permission set for the KMS. Essentially we save the permissions as a bitset (represented as an integer) to the database, with the bits representing the credential type.

These are a few examples of permission types: 1 - Unspecified keys only 2 - Vaccines only 3 - Vaccines and Unspecified 4 - Tests only 5 - Tests and Unspecified 6 - Tests and vaccines 7 - All three.