Add missing web app SKUs, including P0V3

[jwthomson]

This PR addresses #1104

The changes in this PR are as follows:

• Adds the following web app SKUs:
  • Entry level: P0V3
  • Memory optimised: P1MV3 P2MV3 P3MV3 P4MV3 P5MV3

I have read the contributing guidelines and have completed the following:

• [ ] Tested my code end-to-end against a live Azure subscription.
• [ ] Updated the documentation in the docs folder for the affected changes.
• [ ] Written unit tests against the modified code that I have made.
• [x] Updated the release notes with a new entry for this PR.
• [x] Checked the coding standards outlined in the contributions guide and ensured my code adheres to them.

If I haven't completed any of the tasks above, I include the reasons why here:

I couldn't find any docs or tests to extend with this extra SKU. Since the change is just a convenient mapping of PremiumV3 "P0V3", PremiumV3 "P1MV3" etc., so I feel like it is reasonable to skip these.

Below is a minimal example configuration that includes the new features, which can be used to deploy to Azure:

#r "nuget: Farmer"

open Farmer
open Farmer.Builders

let app = webApp {
    name "my-web-app"
    sku WebApp.Sku.P0V3
}

let deployment = arm {
    add_resource app
}

Deploy.execute "my-rg" [] deployment