- update: major refactor of the database-service to make it easy to add newer api services

- add: character database api

proto/user_db_api.proto

@@ -0,0 +1,40 @@
+syntax = "proto3";
+
+package user_db_api;
+
+service UserService {
+    rpc GetUser(GetUserRequest) returns (GetUserResponse);
+    rpc CreateUser(CreateUserRequest) returns (CreateUserResponse);
+    rpc GetUserByUsername(GetUserByUsernameRequest) returns (GetUserResponse);
+    rpc GetUserByEmail(GetUserByEmailRequest) returns (GetUserResponse);
+}
+
+message GetUserRequest {
+    int32 user_id = 1;
+}
+
+message GetUserByUsernameRequest {
+    string username = 1;
+}
+
+message GetUserByEmailRequest {
+    string email = 1;
+}
+
+message GetUserResponse {
+    int32 user_id = 1;
+    string username = 2;
+    string email = 3;
+    string hashed_password = 4;
+    repeated string roles = 5;
+}
+
+message CreateUserRequest {
+    string username = 1;
+    string email = 2;
+    string hashed_password = 3;
+}
+
+message CreateUserResponse {
+    int32 user_id = 1;
+}