This function is used by Ignition's Expression language.
Returns true if the user has the given role. The username and usersource parameters are optional in the client scope, but required in the Gateway scope.
hasRole(role[, username][, usersource])
string role - The name of a role.
string username - Optional. A username. Defaults to the current user.
string usersource - Optional. The usersource of the username. Defaults to the usersource of the current user.
Bool - True if the specified user has the specified role, False if not.
// This is an example using a username and userSource:
hasRole("Administrator", "bob", "default")
// This is an example using the current user and default userSource in the client scope:
hasRole("Administrator")