Is your feature request related to a problem? Please describe.
Argo CD image updater v1.0.0 removes the support for Applications in any namespace. My current setup (using v0.17.0) is based on a multi-tenant way of configuring Applications in each tenant's namespace. Previous versions, where you specified the Argo CD Image Updater configuration as annotations on the Application, multiple namespaces were supported.

Describe the solution you'd like
Make Argo CD Image Updater compatible with the Argo CD Applications in any namespace feature.

Describe alternatives you've considered
Without this feature is implemented, I'd need to move tenant Applications to the Argo CD namespace before upgrading to v1.0.0. While this is certainly possible, it would introduce concerns related to RBAC/security.

Additional context
The documentation clearly states that this feature is not currently supported, but I believe it would be valuable for the community to have an issue where progress and discussions around this functionality can be tracked.