Allow changing the name of the integer primary key

[LHolten]

The current integer primary key name is "id" which is likely to be a column name that developers want to use.

[LHolten]

I thought of a very clean way to do this: we can just allow users to mark a single column unique constraint as primary.
Effectively this allows many things at the same time:

• changing the name of the primary key
• changing the type of the primary key
• reading the value of the primary key
• allow editing the primary key, for this all foreign keys should have ON UPDATE CASCADE.
  Editing primary keys can potentially be forbidden if there is no index on all foreign keys to it.
• we can mark the table as WITHOUT ROWID (https://sqlite.org/withoutrowid.html) for performance.
• we can optimize queries to not join if only the primary key is used.
• potential to allow primary keys with multiple columns in the future.

[LHolten]

We can go in a different direction and make support for integer primary keys more flexible.
It might be useful to just accept any schema with an integer primary key, whatever the name.
(Important is that the integer primary key is named, because SQLite gives less guarantees for the implicit row_id)