Support webapp deploy --async false for src-uri deployments

**Related command**
`az webapp deploy --name 'app' --resource-group 'a[[-rg' --slot staging --async false --clean true --restart true --type zip --src-uri 'https://test.blob.core.windows.net/deployments/app-v1.0.0.zip'`

**Is your feature request related to a problem? Please describe.**
Support sync request so the command waits until it has been fully deployed. Otherwise we cannot easily use `terraform` to deploy the app

**Describe the solution you'd like**
Fully support the `--async false` argument for `--src-uri` style of deployment

**Additional context**
There isnt even a command you can call repeatedly to see if the app has deployed; its really a complete unknown as to whether the command has worked, completed, failed or is inprogress and as such is not very useful