Add support for using SQLite in tests (opt-in)

[srtfisher]

Depends on alleyinteractive/mantle-ci#11

Adds opt-in support for using SQLite in tests in place of MySQL. Uses the db.php drop-in from https://github.com/aaemnnosttv/wp-sqlite-db

[nlemoine]

Hi @srtfisher,

Looks like SQLite is on its way to core. Why not using the official implementation?

Amazing work on Mantle by the way!

[anubisthejackle]

🎸

[anubisthejackle]

Why not using the official implementation?

I think the main reason I can see is that the official plugin isn't a simple drop-in db.php which is what we're using for testing purposes.

[srtfisher]

@nlemoine I'd love to! That is actually handled over in our CI script that we use (alleyinteractive/mantle-ci#11) and I can add a TODO to my list to review switching it over. I will second @anubisthejackle here and say that it was mighty simple to get a single db.php added versus a whole set of files from the plugin. Hopefully we can switch over to core's https://wordpress.org/plugins/sqlite-database-integration/ soon enough.