Proposed title of this feature request

proxy should be configurable for all output types

What is the nature and description of the request?

Add a `proxy:` field to the all output where the user can provide a proxy URL to be used by that output only.

Why does the customer need this? (List the business requirements)

An OpenShift admin wants to proxy to be configurable for all outputs mentioned in doc[0] like below RFE[1]:

[0] https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html/logging/logging-6-2#clf-outputs_6-2_logging-6x-6.2

[1] https://issues.redhat.com/browse/OBSDA-877