az quota commands should support Microsoft.Web

**Related command**
az quota

**Is your feature request related to a problem? Please describe.**
The `az quota` command can be used to see and request quota increases for Microsoft.Compute, but cannot be used to see or request quota increases for App Service plans (Microsoft.Web).

Since quotas for App Service plans exist, we need to manually create support tickets with Microsoft to increase these quotas.

When deploying to customers infrastructure and encountering quota errors, we need to get customers to manually request quota increases from Microsoft.

**Describe the solution you'd like**
Commands like this should work:
``` bash
az quota usage list \
--scope "subscriptions/${SUBSCRIPTION_ID}/providers/Microsoft.Compute/locations/australiaeast"
```

**Describe alternatives you've considered**
There appears to be no alternatives right now, other than creating tickets with Microsoft.

**Additional context**
Examples of error messages we get when trying to provision app service plans that are blocked by quota:
> Failed to create app service plan xxx in resource group yyy: Operation returned an invalid status 'Unauthorized'
Content: {"Code":"Unauthorized","Message":"Operation cannot be completed without additional quota. \r\nAdditional details- Location: \r\nCurrent Limit (PremiumV3 VMs): 0 \r\nCurrent Usage: 0\r\nAmount required for this deployment (PremiumV3 VMs): 1 \r\n(Minimum) New Limit that you should request to enable this deployment: 1. \r\nNote that if you experience multiple scaling operations failing (in addition to this one) and need to accommodate the aggregate quota requirements of these operations, you will need to request a higher quota limit than the one currently displayed.","Target":null,"Details":[{"Message":"Operation cannot be completed without additional quota. \r\nAdditional details- Location: \r\nCurrent Limit (PremiumV3 VMs): 0 \r\nCurrent Usage: 0\r\nAmount required for this deployment (PremiumV3 VMs): 1 \r\n(Minimum) New Limit that you should request to enable this deployment: 1. \r\nNote that if you experience multiple scaling operations failing (in addition to this one) and need to accommodate the aggregate quota requirements of these operations, you will need to request a higher quota limit than the one currently displayed."},{"Code":"Unauthorized"},{"ErrorEntity":{"ExtendedCode":"70007","MessageTemplate":"Operation cannot be completed without additional quota. \r\nAdditional details- Location: {0} \r\nCurrent Limit ({1}): {2} \r\nCurrent Usage: {3}\r\nAmount required for this deployment ({1}): {4} \r\n(Minimum) New Limit that you should request to enable this deployment: {5}. \r\nNote that if you experience multiple scaling operations failing (in addition to this one) and need to accommodate the aggregate quota requirements of these operations, you will need to request a higher quota limit than the one currently displayed.","Parameters":["","PremiumV3 VMs","0","0","1","1"],"Code":"Unauthorized","Message":"Operation cannot be completed without additional quota. \r\nAdditional details- Location: \r\nCurrent Limit (PremiumV3 VMs): 0 \r\nCurrent Usage