dynamic_modules: support network filters to be terminal (#42751)

## Description

This PR supports Dynamic Modules for network filters to make them
`terminal`.

---

**Commit Message:** dynamic_modules: support network filters to be
terminal
**Additional Description:** Added support for Dynamic Modules for the
network filters to make them `terminal`.
**Risk Level:** Low
**Testing:** Added Tests
**Docs Changes:** Added
**Release Notes:** N/A

Signed-off-by: Rohit Agrawal <[email protected]>

Mirrored from https://github.com/envoyproxy/envoy @ 50ad55a80663a5c40fa172c9cfe951fca76aa17d

Author: update-envoy[bot]

envoy/extensions/filters/network/dynamic_modules/v3/dynamic_modules.proto

@@ -68,4 +68,9 @@ message DynamicModuleNetworkFilter {
   //    value: aGVsbG8=  # echo -n "hello" | base64
   //
   google.protobuf.Any filter_config = 3;
+
+  // Set true if the dynamic module is a terminal filter to use without an upstream connection.
+  // The dynamic module is responsible for creating and sending the response to downstream.
+  // If not specified, defaults to false.
+  bool terminal_filter = 4;
 }