Allow setting ForcedTags using the acls.hujson config file

[networkException]

This pull request introduces a declarative way to set ForcedTags on nodes by recursively expanding aliases. These declarative forced tags are considered separately from the ones stored in the database.

Continuation of #1490

{
    "hosts": {
        "a": "fd7a:115c:a1e0::1",
        "b": "fd7a:115c:a1e0::2"
    },
    "forcedTags": {
        "tag:some-tag": [
            "a",
            "tag:some-other-tag"
        ],
        "tag:some-other-tag": [
            "b"
        ]
    }
}

• [x] read the CONTRIBUTING guidelines
• [x] raised a GitHub issue or discussed it on the projects chat beforehand
• [x] added unit tests
• [ ] added integration tests
• [ ] updated documentation if needed
• [ ] updated CHANGELOG.md