Allow property iteration for runtime properties

Originally discussed in #4555

---

Today, you cannot provide an array from a runtime reference to a loop like so:

```bicep
resource childDomain 'Microsoft.Network/dnsZones@2018-05-01' = {
name: 'child.${baseDomainName}-domain.io'
location: location
}

resource childDomainDelegation 'Microsoft.Network/dnsZones/NS@2018-05-01' = {
name: '${baseDomainName}-domain.io/child'
properties: {
// *** not allowed since childDomain.properties.nameServers is a runtime reference ***
NSRecords: [for dnsServer in childDomain.properties.nameServers: {
nsdname: dnsServer
}]
}
}
```

But it sure would be nice if you could! Otherwise, you need to hack around this limitation with modules as discussed in the referenced issue.

Start with the runtime property and loop behavior shown in this issue, then read the workaround discussed in #4555. Define how childDomain.properties.nameServers can be iterated in the NSRecords expression; the work is done when the shown expression is accepted and produces the expected DNS delegation records.

Written by the indexing model from the issue text.