sds: add ability to reload TLS session ticket keys (#8635)

Description: Finish migration of TLS session ticket keys to provider-based API.
Risk Level: Medium
Testing: added new tests
Docs Changes: updated
Release Notes: updated
Fixes #7397

Signed-off-by: Ruslan Nigmatullin <elessar@dropbox.com>

Mirrored from https://github.com/envoyproxy/envoy @ 55ab495b404eea4700fd5fc91ad31057334b37e6

envoy/api/v2/auth/cert.proto

@@ -377,7 +377,7 @@ message DownstreamTlsContext {
     // TLS session ticket key settings.
     TlsSessionTicketKeys session_ticket_keys = 4;
 
-    // [#not-implemented-hide:]
+    // Config for fetching TLS session ticket keys via SDS API.
     SdsSecretConfig session_ticket_keys_sds_secret_config = 5;
   }
 }

envoy/api/v3alpha/auth/cert.proto

@@ -380,7 +380,7 @@ message DownstreamTlsContext {
     // TLS session ticket key settings.
     TlsSessionTicketKeys session_ticket_keys = 4;
 
-    // [#not-implemented-hide:]
+    // Config for fetching TLS session ticket keys via SDS API.
     SdsSecretConfig session_ticket_keys_sds_secret_config = 5;
   }
 }