[lib] RoleInfo -> LegacyRoleInfo

Summary:
All usages of RoleInfo have been updated to support MinimallyEncodedRoleInfo except for

• createInitialRolesForNewThread
• fetchRoles
• addDetailedThreadEditPermissionsToRole
• addManagePinsThreadPermissionToRole

The first two usages are "between" keyserver and MariaDB. Roles/permissions will continue to be encoded the "old way" in DB for timebeing so updating to handle MinimallyEncodedRoleInfo doesn't make sense.

The second two usages are one-time migrations, so it doesn't make sense to update those.

Test Plan: Just a simple rename so counting on flow/CI/etc.

Reviewers: ashoat, ginsu, tomek, rohan

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D10066