Integrate pytest-lazy-fixtures into core?

A very old and common question is "how can I use fixtures for parametrization?" (#349). During the 2016 sprint we had a discussion which resulted in a proposal, but neither approaches proposed there were implemented into the core.

Meanwhile @TvoroG went ahead and implemented the 2nd approach in an external plugin, pytest-lazy-fixture, which seems to work well in practice.

So how about we integrate that into the core? @TvoroG, is that something you would be willing to contribute?

Alternatively we do not integrate it into the core right now, but officially declare that using pytest-lazy-fixture is the recommended way to go for using fixtures for parametrization (just as pytest-xdist is the official plugin to use for distributed testing). This way we can decide later to merge (if ever) depending on user feedback. This will probably also increase the visibility of the plugin, giving us a chance of seeing the plugin in the wild.

I think the latter is "zero effort/high reward" because we can just add it to the docs, close the relevant issues and let users try it out immediately; the plugin doesn't seem to be very well known at the moment, I was just asked again by a coworker this question and this motivated me to write this proposal/question.

Thoughts?

Start by reading the linked parametrize-with-fixtures proposal and the pytest-lazy-fixture plugin, then review the discussion in this issue. Determine whether the scope is core integration or documenting the plugin as the recommended approach. Done means the chosen direction is agreed and its implementation or documentation work is completed.