Investigation/design for waypoints in ambient mode

[mjnagel]

Related to #681

During initial investigations of istio ambient we discovered that certain functionality will require deployment/usage of Waypoints. In particular (within core) Keycloak and Authservice/authservice protected applications will require waypoint proxies (see #1029 and #1031). We

Definition of done should be a design doc/proposal that ensures an option to deploy waypoints, considering these items in particular:

• Option to deploy a waypoint, via the package CR (consider applications on top of core)
• Automated deployment of waypoints when necessary (i.e. Authservice integration?)
• Management/integration of this through the operator (see docs on using waypoints)
• Considerations on single vs multiple waypoints (see cross-namespace waypoint docs)
• Backwards compatibility for the Package CR!

[mjnagel]

#1142 may be a helpful reference for waypoint functionality as well.