Linter - Improve template governance by supporting metadata linting

[audhage]

Is your feature request related to a problem? Please describe.
The metadata keyword is great for improving template governance. We can implement metadata properties like: version or author.
While the existence and formatting of these "properties" are easy to validate programmatically by compiling the template and extracting the properties, we are unable to have rules stating that certain properties are required, and even potentially the formatting of those properties through VS Code.

Describe the solution you'd like

Some options could include:

Require properties

An option in the .bicepconfig linter options where I can specify required metadata properties.

Example:

// bicepconfig.json
{
// ...
  "analyzers": {
    "core": {
      "rules": {
        "required-metadata-properties": {
          "level": "Error",
          "properties": [
            "author",
            "version"
          ]
        }
      }
    }
  }
// ...
}

Require version property

The most important property to have would be the version property. With this option, it could enforce the semver format for the property.

Example:

// bicepconfig.json
{
// ...
  "analyzers": {
    "core": {
      "rules": {
        "require-metadata-version-property": {
          "level": "Error"
        }
      }
    }
  }
// ...
}