Use the launcher in k8s

1. Add krun to the istio-proxy container ( using a separate name - example istio/mesh-proxy )
2. On init, copy the statically linked binary to a volume (/var/lib/mesh/bin ?)
3. On startup, based on config use a UDS socket to communicate with the proxy container to coordinate startup/shutdown

This can be used with a minimal injection template:
- "mesh" volume
- init and proxy container with no extra CLI or env variables, mounting only "mesh"
- app mounting "mesh", with command line modified to have /var/lib/mesh/bin/krun in first position.

It is also simple enough to be used by users manually, without injection ( or using CI/CD )

We discussed this in Istio env WG, as an alternative to current startup hacks.
Using krun also allows auto-discovery of the config cluster and XDS server, and consistency with Docker/CloudRun where separate containers are not possible.