[wip] adding loose ordering of rules

[freedge]

when updating a large security rule group, one action=move API call is made for each rule of the security rule group, the first rule is placed according to the group position, then each succeeding rule is moved after the previous one.

We introduce a loose ordering of rules where we only order newly created rules and put them below any other rule of the security group. This considerably reduces the amount of API calls needed to update rules.

https://github.com/PaloAltoNetworks/terraform-provider-panos/issues/378

How Has This Been Tested?

tested using the matching terraform-provider-panos change (not submitted). My security group rule contains 900 elements, the overall terraform plan/update (that does much more than just the rules) goes from 1m30s to 1m in local, where there is no communication delay between terraform and the NGFW.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist

• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes if appropriate.
• [x] All new and existing tests passed.