Story (Required)

As a user wanting to use multi-source applications in Argo CD, I want to create a multi-source application using the New App dialog in the UI, and also be able to view and edit an already deployed multi-source application in the UI.{}

Background (Required)

Previous work for multiple sources:  https://github.com/argoproj/argo-cd/blob/master/docs/proposals/multiple-sources-for-applications.md

Multiple sources for applications has been introduced in ArgoCD, but still needs UI support as an additional feature. 
See https://github.com/argoproj/argo-cd/blob/master/docs/proposals/multiple-sources-for-applications.md#changes-to-ui 

See PR changes: https://issues.redhat.com/browse/GITOPS-3797

Out of scope

Implementation of the feature.

Proposal for the design changes in the CLI is out of scope

Approach (Required)

Make a PR detailing feature to upstream ArgoCD in the following format: https://github.com/argoproj/argo-cd/blob/master/docs/proposals/001-proposal-template.md 

Dependencies

Acceptance (and any requests for changes) from the upstream Argo CD community.

Acceptance Criteria (Mandatory)

• Create proposal for CLI support for multiple sources
• Present proposal to Argo CD Community
• Get proposal accepted 

Done Checklist

• Code is completed, reviewed, documented and checked in
• Unit and integration test automation have been delivered and running cleanly in continuous integration/staging/canary environment
• Continuous Delivery pipeline(s) is able to proceed with new code included
• Customer facing documentation, API docs etc. are produced/updated, reviewed and published
• Acceptance criteria are met