Add ability for webapp vnet integration

[l3ender]

SUMMARY

This is a request for the ability to add webapp vnet integration, so that networking configuration can be defined for a web app.

ISSUE TYPE

• Feature Idea

COMPONENT NAME

azure_rm_webapp_vnetintegration – Manage Web App Virtual Network Integrations.
azure_rm_webapp_vnetintegration_info – Get Web App Virtual Network Integration facts.

ADDITIONAL INFORMATION

This would allow someone to associate a virtual network with a web application.

- name: "Configure virtual network for web app."
  azure.azcollection.azure_rm_webapp_vnetintegration:
    resource_group: "MyResourceGroup"
    name: "MyWebapp"
    virtual_network_name: "MyVnetName"
    subnet: "MySubnetName"

Please offer thoughts/corrections to above naming. I plan to add a PR to support this feature and would like feedback in advance, if possible!