Update OLO/WLO to 1.2.0 and enable automatic offer update

[majguo]

The PR includes the following major enhancements:

• Update OLO/WLO to 1.2.0
• Enable automatic offer update using the latest release microsoft/microsoft-partner-center-github-action@v3
• Add a doc about how to update offer in partner center
• Run same arm-ttk tests executed in partner center pipeline

Testing

The following runs of integration-test workflow successfully completed:

• AppGW + WLO: integration-test-99
• AppGW + OLO: integration-test-98
• WLO: integration-test-97
• OLO: integration-test-96

Signed-off-by: Jianguo Ma jiangma@microsoft.com