Add Forced Tunneling to the Hub Firewall configuration

[Phydeauxman]

Description

This PR enables forced tunneling the firewall deployment by adding a management subnet to the hub virtual network, creating a route table applied to the management subnet with a default route to the Internet and adding a management IP config to the firewall.

Issue reference

The issue this PR will close: #117

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

[glennmusa]

We'll need to add the time provider to src/Dockerfile too

[glennmusa]

added the do-not-merge label for the time being until docs are up-to-date with guidance on forced tunneling @Phydeauxman -- feel free to remove it whenever