Bicep deploy - discuss/improve output channel design

Currently in bicep deploy feature, we show the output channel when deployment starts and it is open till we report success/failure. @StephenWeatherford raised concern here-https://github.com/Azure/bicep/pull/6129#discussion_r827428905 regarding the same and suggested we show the output channel when deployment starts and when it completes or errors out and not during progress logging. This issue is logged discuss the design and make improvements.