API connection needs to support connectionRuntimeUrl as output/property

**Bicep version**

```bash
$ az bicep version
Bicep CLI version 0.4.63 (7ebed03284)
```

**Describe the bug**

I'm creating an API Connection resource in Azure so that I can then use its Runtime URL in a Logic App connection. However, I'm unable to get the runtime URL despite it being available on the API Connection resource's output from `az cli`

**To Reproduce**
Steps to reproduce the behavior:

```bicep
resource tableStorageConnection 'Microsoft.Web/connections@2016-06-01' = {
name: 'tablestorage'
location: resourceGroup().location
properties: {
displayName: 'tablestorage'
api: {
id: '/subscriptions/${subscription().subscriptionId}/providers/Microsoft.Web/locations/${resourceGroup().location}/managedApis/azuretables'
}
}
tags: tags
}
```

now try to get the `connectionRuntimeUrl` property off the created Azure resource as shown by `az resource show --ids `:
```json
"properties": {
"api": {
"brandColor": "#804998",
"category": "Standard",
"description": "Azure Table storage is a service that stores structured NoSQL data in the cloud, providing a key/attribute store with a schemaless design. Sign into your Storage account to create, update, and query tables and more.",
"displayName": "Azure Table Storage",
"iconUri": "https://connectoricons-prod.azureedge.net/releases/v1.0.1479/1.0.1479.2452/azuretables/icon.png",
"id": "/subscriptions/xxxxx/providers/Microsoft.Web/locations/westus2/managedApis/azuretables",
"name": "azuretables",
"type": "Microsoft.Web/locations/managedApis"
},
"authenticatedUser": {},
"changedTime": "2021-07-06T21:25:02.8856356Z",
"connectionRuntimeUrl": "https://xxxxx.common.logic-westus2.azure-apihub.net/apim/azuretables/xxxxx",
"createdTime": "2021-07-06T21:25:02.8856356Z",
"customParameterValues": {},
"displayName": "tablestorage",
"nonSecretParameterValues": {
"storageaccount": "default"
},
```

I tried by using

`tableStorageConnection.properties.connectionRuntimeUrl` and `tableStorageConnection.properties['connectionRuntimeUrl']`

and am met with the following _warning_ in the CLI during deployment

```shell
/main.bicep(54,54) : Warning BCP053: The type "schemas:30_properties" does not contain property "connectionRuntimeUrl". Available properties include "api", "changedTime", "createdTime", "customParameterValues", "displayName", "nonSecretParameterValues", "parameterValues", "statuses", "testLinks".
```

but the deployment then **fails** in Azure with the same message:

(Secondary complaint: if it's going to fail the deployment, then bicep should error, not warn)

Bicep's compiled JSON looks like this:
```json
// where I'm trying to use the value
{
"name": "azuretables_runtimeUrl",
"value": "[reference(resourceId('Microsoft.Web/connections', 'tablestorage')).connectionRuntimeUrl]"
},
...
{
"type": "Microsoft.Web/connections",
"apiVersion": "2016-06-01",
"name": "tablestorage",
"location": "[resourceGroup().location]",
"properties": {
"displayName": "tablestorage",
"api": {
"id": "[format('/subscriptions/{0}/providers/Microsoft.Web/locations/{1}/managedApis/azuretables', subscription().subscriptionId, resourceGroup().location)]"
}
},
"tags": "[parameters('tags')]"
}

```

Start at the type definition for Microsoft.Web/connections@2016-06-01 and reproduce the issue with the Bicep resource shown in the report. Check how connectionRuntimeUrl is represented and how the resulting reference diagnostic is emitted. Done means the property is handled consistently with the Azure resource output and the reported invalid deployment case is diagnosed appropriately.

Written by the indexing model from the issue text.