Azure trusted signing with service connection

[erijo]

The requirement to set AZURE environment variables interferes with the use of service connection to connect to the service from a devops pipeline (similar to this example).

I've gotten it to work by:

1. First running the AzureCLI@2 task to access the service connection and export the three environment variables.
2. Use az in a separate step to log in using the variables from step 1.
3. Run electron-builder with the environment variables set as this:

• AZURE_TENANT_ID=$(ARM_TENANT_ID)

• AZURE_CLIENT_ID='dummy'

• AZURE_CLIENT_SECRET='dummy'

  and this in azureSignOptions:

• "ExcludeEnvironmentCredential": "-Debug"

That will use the AzureCliCredentials. If the environment variables weren't required I think I wouldn't have to give dummy values nor pass the -ExcludeEnvironmentCredential flag to Invoke-TrustedSigning.