Design and implement activity storing system

**Is your feature request related to a problem? Please describe.**
We get a bunch of different events from GitHub API: issues, PRs, releases, repositories, users.

**Describe the solution you'd like**
There is a need to standardize this data within a separate entity. Each record should be linked to a project/repo and user (normally we have this data). After indexing it we can use it for project and user timelines on corresponding Nest pages.

**Additional context**
https://docs.github.com/en/rest/activity/events?apiVersion=2022-11-28#list-public-events