support oci image as a code source for wasm

[zhaohuabing]

Majority of the WASM Modules now live in OCI Registries, so EG should be able to set an OCI image as the WASM code source through its API. There are two ways to accomplish this:

• Envoy supports oci_uri as a remote code source for its wasm filter, which is not supported yet, tracked in upstream issue support oci_uri as a remote data source for wasm envoy#33212
• EG fetches wasm modules from OCI registries and serves the envoy proxies through a control plane side HTTP server.