1- Proposed title of this feature request
Add GPG validation support to multi source Applications.

2- What is the nature and description of the request?
GPG validation is already supported for single source Applications, add this support to multi source Applications.

3- Why does the customer need this? (List the business requirements here)
We'd like to migrate to multi source applications to simplify our code, but have a strict requirement for GPG validation which prevents us using multi source Applications.

4- How would the customer like to achieve this? (List the functional requirements here)
Add GPG support to multi source Applications.

5- For each functional requirement listed, specify how Red Hat and the customer can test to confirm the requirement is successfully implemented.
Create the two examples in the docs - https://argo-cd.readthedocs.io/en/latest/user-guide/multiple_sources/ - but with GPG validation enabled.

6- Would the customer be able to assist in testing this functionality if implemented?
Yes