Testing azdev publish with AzureFirewall

[tjprescott]

Some minor fixes to AzureFirewall to test the azdev build and azdev publish commands.

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This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines

• Have you run ./scripts/ci/test_static.sh locally? (pip install pylint flake8 required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

[azuresdkci]

If this PR is for a new extension or change to an existing extension, use the following to try out the changes in this PR:

docker run -it microsoft/azure-cli:latest
export EXT=<NAME>
pip install --upgrade --target ~/.azure/cliextensions/$EXT "git+https://github.com/Azure/azure-cli-extensions.git@AzureFirewallUpdate#subdirectory=src/$EXT&egg=$EXT"