Promoting Azure best practices

There is a set of best practices that we as Azure are recommending to customers. For example, using the managed identity for secretless auth. It would be great if we could allow customers to opt into getting diagnostics about best practices they like.

For example the following snippet would produce a diagnostic

```bicep
resource frontend 'Microsoft.Web/sites@2021-01-15' = {
}
```

With a hot fix resulting in:

```bicep
resource frontend 'Microsoft.Web/sites@2021-01-15' = {
identity: {
type: 'SystemAssigned'
}
}
```

Maybe we can integrate with some [Azure Advisor](https://azure.microsoft.com/en-us/services/advisor/#overview) rules to shift suggestions to the development time.

No repository file, test, or entry point is named. Start by reviewing the Bicep example and the linked Azure Advisor rules to determine how opt-in best-practice diagnostics would fit; done requires a defined set of rules, opt-in behavior, and diagnostic or hot-fix expectations.

Written by the indexing model from the issue text.