Isolated tests

[kenbot]

Alrighty! That was a piece of work.

• TestFile has been rewritten to have isolated Initialize and Cleanup, where the database table is cleared after each one
• Removed code which was specifying primary keys for inserted records, which works the first time, but Sqlite will ignore it and pick a different ID if you try to enter the same record again later. This is confusing behaviour and isn't realistic prod behaviour anyway. The TestUtil.EqualsIgnore method comes in handy here.
• Removed the iterating insertions, which is wasteful and wasn't exposing meaningful cases.
• Using minimal bespoke fixtures, which apart from being mildly fun, allow a tight focus on corner cases, reduce the chance of false positives from inbred test data, and make debugging really easy.
• Extracted TestIWad from TestGameFile and rewrote it in the same way
• Changed DbDataSourceAdapter to expose DataAccess publicly, and hide ConnectionString and DatabaseAdapter, which is a solid encapsulation win and simplifies cleanup code & TestInit.
• Rewrote TestGameFile and TestLoadFiles in the same way
• Fixed latent bug: parameters were swapped in DbDataSourceAdapter.UpdateGameFiles
• Fixed latent bug: accessing member variable instead of method argument in FileLoadHandler.GetIWadFilesFromGameFile

[nstlaurent]

This looks good to me! 👍

[kenbot]

Sorry to bother you @nstlaurent, would you mind taking a look? I'm going to have a bunch of free time coming my way shortly, and I need fast, deterministic tests to get started