feat: adding Azure Network module

[davesee]

Adding the following modules
Virtual Network and Subnet
Network Interface
Public IP Address

Adding the Terratest Network example to test these modules

Fixes #627

[rguthriemsft]

Resolves #627

[rguthriemsft]

Here is the CI run for this pull request https://github.com/rguthriemsft/terratest/runs/1120097907?check_suite_focus=true

[davesee]

Update CI pass: https://github.com/rguthriemsft/terratest/runs/1160971866?check_suite_focus=true

[davesee]

https://github.com/rguthriemsft/terratest/runs/1166999608?check_suite_focus=true

[yorinasub17]

Mostly LGTM! Most comments are style nits. There is one substantial comment about returning the error in the Exists functions.

[davesee]

CI Passed: https://github.com/rguthriemsft/terratest/runs/1178644697?check_suite_focus=true

[davesee]

https://github.com/rguthriemsft/terratest/runs/1183265701?check_suite_focus=true

[davesee]

CI Pass: https://github.com/rguthriemsft/terratest/runs/1185578138?check_suite_focus=true

[yorinasub17]

The latest updates LGTM! However, after checking the build log, I noticed that it is running the old version that doesn't have the terraform fmt check and modules unit tests.

Can you rebase and rerun the build so it does those checks?

[davesee]

Sorry about that @yorinasub17, the files were updated but I re-ran the earlier workflow ci-job. Here is a new run/pass with the fmt and unit tests:

https://github.com/rguthriemsft/terratest/runs/1187932044?check_suite_focus=true

[yorinasub17]

LGTM! Thanks for working through the fixes.