Abstract `RestService`, `RestRequest` and `RestHandler`

[vladyslav-fenchak]

Currently the flow is:

1. RestService is in charge of start the REST service interface si
2. it calls RestHandler which sets up the routes and everything necessary to handle and redirect the request/response.
3. RestRequest which is responsible of parsing the request.

This would require:

• Decouple aiohttp REST from request/response wrapper.
• Create common aiohttp wrapper.