[Research] Check how to do database migrations with room

[aniri]

• research how db migrations are handled in room
• prepare a small proof of concept - one small migration example (ex. add new column; rename column)
• set up unit tests for migration

See: https://developer.android.com/training/data-storage/room/migrating-db-versions

[DeKaN]

I can take this issue

[aniri]

closing this issue at is was covered in the pull request #72 . the PR will be merged when the first migration will be needed 😄