[Feature]: New-AzAutomationSourceControl should support OAuth instead of Personal Access Token

### Description of the new feature

In the documentation: https://learn.microsoft.com/en-us/powershell/module/az.automation/new-azautomationsourcecontrol?view=azps-10.4.1#example-1 it is stated to use a VSTS Personal Access Token to link a VsoGit repository. With the support of Service Principals and Managed Identities, it would be useful to use OAuth instead. Now you have to do a bit of a workaround when using for example a UAMI. You can't grant the Azure DevOps API permission and granted admin consent on a UAMI.

Therefore, you've to build your custom API call like so:
```powershell
$AccessToken = (Get-AzAccessToken).Token
$Body = @{
name = $SourceControlName
properties = @{
repoUrl = $RepoUrl
sourceType = 0
branch = $Branch
folderPath = $FolderPath
autoSync = $false
publishRunbook = $true
securityToken = @{
accessToken = $AccessToken
refreshToken = $AccessToken
tokenType = 'oauth'
}
}
}

$PayLoad = ($Body | ConvertTo-Json -Depth 100 -Compress)

$Headers = @{
'Authorization' = "Bearer $AccessToken"
'Content-Type' = 'application/json; charset=utf-8'
}

Write-Information -MessageData ("Invoking 'Invoke-RestMethod' against URI [ {0} ]" -f $ApiUri) -InformationAction Continue
$Res = Invoke-RestMethod -Method Put -Uri $ApiUri -Body $PayLoad -Headers $headers
```
### Proposed implementation details (optional)

_No response_

Start with the New-AzAutomationSourceControl entry point and the linked Microsoft Learn example for its current Personal Access Token flow. Compare that documented request with the OAuth payload and Invoke-RestMethod example in the issue, then identify the repository's existing source-control tests or implementation before choosing a design. Done means the cmdlet supports the requested OAuth authentication path without requiring the workaround.

Written by the indexing model from the issue text.