Allow selecting multiple roles with multi-party-approval

[kbelosevic]

If MPA is configured, we are only allowed to select only one role at a time.

We have a situation for infrastructure engineers (i.e. terraform) that will require a lot of roles at a time, so clicking daily on multiple roles is cumbersome.

Even when creating Custom IAM roles, we still have limit on number of permissions and etc so we end up having multiple custom roles.