Committing changes related to program service join and invite role

[Azher2Ali]

Issue:- When following the invite user and join program flow, using the HTTP endpoints, the role is not captured/returned. The user details in the program users list report the user role as null. (#432)

Solution- By adding a DEFAULT enum value at 0 position into User Role Value under protocol file. This DEFAULT value will only be used as placeholder and will never be used for any Role Type.

[joneubank]

Changing a protobuff in this way carries some risk. Specifically any existing server that doesnt use the updated proto file will be interpretting UserRole enum of 1 as ADMIN while the server believes that is COLLABORATOR, this could cause real errors. Additionally, we don't want to have a role of DEFAULT. If this is fixing our problem its only because our converter is not handlign the default case, not because we need a role called DEFAULT.

[Azher2Ali]

In regards to changes related to enum value returning as empty at the 0th position (COLLABORATOR) in the proto enum.Therefore, moving COLLABORATOR from 0th position to 5th position without affecting other existing values within the enum, adding a DEFAULT value at the 0th position.