Table to store data from `UserStore` in SQLite.
Column types are based on [Flow types](https://github.com/CommE2E/comm/blob/b49929e80a2b2170bb04c086987ceb4cb95e9439/lib/types/user-types.js#L34).
Some time ago @atul suggested to make this table key-value with data in JSON - I still think for some stores it's beneficial but here I decided to make more datailed data representation. Making key-value doesn't speed things up that much, and I think at some point we might want to have easy access to user data from C++/Rust (for example avatar to show more detailed notif).
EDIT: actually that was a bad assumption, `avatar` can have multiple types which force us to use JSON anyway which means we will not gain anything, and the amount of C++ code is reduced a lot, that being said proceeding with a simple key-value table.
Depends on D9902