Fix authenticator order

[trucdg]

Fixes AAP-28034: Changes Made:

• Added a get_next_authenticator_order function to find the next order value, which is equals to max(order) + 1
• Added unit test

Testing Steps:

1. Create a new authenticator, and confirm the followings:
   • If given an order, the created authenticator's order = given order value
   • If no order was given, the created authenticator's order = max(order) + 1
2. Update/ Delete the order of the current authenticators
3. Back to step 1 and confirm the authenticator order is as expected

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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