Rewrite migrations statements to contain foreign keys instead of JSON objects

[bitfl0wer]

Depends on completion of Remove Json<T> wrapper from all types which should be broken out into own tables.

The migrations should reflect the relations between tables and table entries correctly, instead of storing relations, which are references to other tables, as JSON. Normally, this is referred to as the "first normal form". Every column which could be represented by a chorus or symfonia type should be represented by these types.