feat(arm): add MariaDbPublicAccessDisabled convert policy to arm

[chani6887]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Description

We converted the check MariaDBPublicAccessDisabled from TERRAFORM language to the ARM language so that it also works on resources that are defined in the ARM language

Description on the check

Ensure that MariaDB server enables geo-redundant backups

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] I have added tests that prove my feature, policy, or fix is effective and works
• [x] New and existing tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules

[ChanochShayner]

Please change the name as well to match the real check (as in Terraform)- name = "Ensure that MariaDB server enables geo-redundant backups"