bf orchestrator:add remove previously added data source #1235

Versions

What CLI version are you using.
4.13.3

Describe the bug

Adding a new data source to orchestrator via bf orchestrator:add command (equivalent to dispatch add command) will remove previously added sources

To Reproduce

1. Add a LUIS/QnA Maker source with the command "bf orchestrator:add". Check orchestrator.settings.json and make sure it has the added data source.
2. Repeat chatdown plugin and bf cli #1 with another LUIS/QnA Maker.

Actual behavior

Data source added in step #1 above is removed from orchestrator.settings.json.

Expected behavior

Newly added data source and previously added data sources are persisted in orchestrator.settings.json.