feat(classification-banner): added a classification banner `EnvoyFilter`

General MR

Summary

This MR is the same as the one recently added to istio-controlplane: istio-controlplane!339 (merged) and merged into BB: big-bang/bigbang!5951 (merged)

Just adding here for feature parity.

Relevant logs/screenshots

Check original MR: istio-controlplane!339 (merged)

Linked Issue

big-bang/bigbang#1559 (closed)

Upgrade Notices

N/A