Port Brave Sync server to Rust

Use SQLite for persistence and generate Rust protobuf bindings at build time.

Add Docker image support for containerized deployment.

Co-Authored-By: codex <[email protected]>

schema/protobuf/sync_pb/password_sharing_recipients.proto

@@ -0,0 +1,41 @@
+// Copyright 2023 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+syntax = "proto2";
+
+option go_package = "./sync_pb";
+
+option java_multiple_files = true;
+option java_package = "org.chromium.components.sync.protocol";
+
+option optimize_for = LITE_RUNTIME;
+
+package sync_pb;
+
+import "password_sharing_invitation_specifics.proto";
+
+// A message to obtain a list of recipients for sending a password.
+message PasswordSharingRecipientsRequest {
+  // The request returns family members for the user and that is why no
+  // additional fields are required.
+}
+
+message PasswordSharingRecipientsResponse {
+  enum PasswordSharingRecipientsResult {
+    UNKNOWN = 0;
+
+    // The user is a member of a family and the request succeeded.
+    SUCCESS = 1;
+
+    // Not a family member, used to distinguish from a family with
+    // only one member.
+    NOT_FAMILY_MEMBER = 2;
+  }
+  optional PasswordSharingRecipientsResult result = 1;
+
+  // List of possible recipients for sending a password. Note that public key
+  // may be absent if a recipient can’t receive a password (e.g. due to an older
+  // Chrome version).
+  repeated UserInfo recipients = 2;
+}