Upgrade PowerShell Functions to 7.2 or greater

# Rule request

## Suggested rule change

Add a new rule `Azure.Function.PowerShellVersion` to configure a minimum version of PowerShell with Azure Functions. Also host version `~4` is required.

Only applies to Azure Functions sites with:

- `FUNCTIONS_WORKER_RUNTIME` set to `powershell`

The selector `Azure.AppService.IsFunctionApp` can be used to only target function apps.

Rule recommendation will be similar to:

- https://azure.github.io/PSRule.Rules.Azure/en/rules/Azure.AppService.NETVersion/
- https://azure.github.io/PSRule.Rules.Azure/en/rules/Azure.AppService.PHPVersion/

## Applies to the following

The rule applies to the following:

- Resource type: **Microsoft.Web/sites** and **Microsoft.Web/sites/slots**

## Additional context

- [Upgrading your Azure Function Apps to run on PowerShell 7.2](https://github.com/Azure/azure-functions-powershell-worker/wiki/Upgrading-your-Azure-Function-Apps-to-run-on-PowerShell-7.2)