add a Bastion Host module

[glennmusa]

Description

Adds an Azure Bastion Host module that can be added to any virtual network given a valid subnet larger than /27.

To know this is working deploy an instance of MLZ and inspect the SACA Hub resource group. With the supplied defaults you should see a mlzDemoBastionHost resource and its accompanying public IP address mlzDemoBastionHostPip reside in a AzureBastionSubnet of 10.0.100.128/27.

Issue reference

The issue this PR will close: #186

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles or validates correctly
• BASH scripts have been validated using shellcheck
• All tests pass (manual and automated)
• The documentation is updated to cover any new or changed features
• Markdown files have been linted using the recommended linter. (See .vscode/extensions.json.)
• Relevant issues are linked to this PR

[brooke-hamilton]

I was able to deploy the bastion host module in a single subscription. All resources were created successfully. No errors.