Unit test for firewall rule order

to ensure that input rule order and output rule order are the same, which should in turn ensure that the target VSE rule order is correct
Ensure remote FirewallService rule order is correct

We need to ensure that the output rule order is correctly mapped to the
input rule order.

This adds a simple test based on ensuring that the rule Descriptions are
in the same order, which gives a high degree of confidence that the rules
themselves match.
Merge pull request #141 from alphagov/firewall-rule-order-test

[#62380500] Firewall rule order test