Fix upsert for WITHOUT ROWID tables with an INTEGER primary key

[nesevis]

As part of testing my testing library against GRDB, this state machine test failed when upserting into a table that was created with a single integer primary key, but without rowid, with the following error:

SQLite error 1: no such column: "rowid" - should this be a string literal in single-quotes?

I've tried to follow the established convention here of commits of failing tests followed by a fix for said tests, so checking out the first commit and running the new tests will reproduce the issue.

I believe this is related to the issue in #1855 from earlier this year, but the fix here is in Database+Schema.swift, which treated an integer primary key as a rowid alias without checking whether its table had one.

Pull Request Checklist

• CONTRIBUTING: You have read https://github.com/groue/GRDB.swift/blob/master/CONTRIBUTING.md
• BRANCH: This pull request is submitted against the development branch.
• DOCUMENTATION: Inline documentation has been updated.
• DOCUMENTATION: README.md or another dedicated guide has been updated. (N/A)
• TESTS: Changes are tested.
• TESTS: The make smokeTest terminal command runs without failure.