Multiple source values ref targetRevision not shown in the main UI out of synch "from"

[gioppoluca]

Summary

When in the multiple source application only the version of the ref values of a helm chart changes there is no clue in the UI

Motivation

We use the change targetRevision of the value.yaml file and we version also that aspect since it can represent a minor change in a deployment, but there is no place to see all the values of the targetRevision in the UI

Proposal

Add in the "from" area the list of all the targetRevision of all sources of a multisource application

[gioppoluca]

linked to #18088