YANGTOOLS-1483 improves ergonomics of unit tests to a large extent: it allows hosting a YANG snippet in Java code.

We have plenty of UT code which could leverage this facility, but migration is tedious for little gain.

openrewrite to the rescue: it allows us to migrate code using a simple recipe, which then is plugged into maven build and performs the transform.

Write such a plugin, which will inline src/test/resources (and remove them) as part of its run.

For now, let's inline any YANG file under 50 lines, which should be a tuneable default.