Add a basic logging to the service

[ochaplashkin]

Description

We are adding logging to the service.
Now, the activity records will be linked via a cross-service unique ID that github sends: X-GitHub-Delivery.

Logs are written in the container's stdout as JSON and are available by the docker logs command.

Usage

1. You tagged the bot and nothing happened;
2. Go to the Settings > Webhooks > docbot > Recent Deliveries;
3. Choose your webhook;
4. Copy X-GitHub-Delivery;
5. Get logs from a DocBot using any tool (docker logs, kibana, etc.);
6. Do grep/search/etc by X-GitHub-Delivery.

E.g result:

[Mar 7, 2023 @16:06:31.893] <X-GitHub-Delivery> Comment has been sent successfully
[Mar 7, 2023 @16:06:30.640] <X-GitHub-Delivery> Request is processed ok
[Mar 7, 2023 @16:06:30.631] <X-GitHub-Delivery> Start <issue_comment> event processing
[Mar 7, 2023 @16:06:30.626] <X-GitHub-Delivery> Accept webhook from GitHub service

Resolves #28