cmd/cue: add first `exp writefs` testscript
We hadn't added one initially because the code was imported from
the cuelang.org repository and we were in a bit of a rush
to make it available for an end user facing slowness.
Now that we can spare a bit of time, and we're going to tweak the code
further and add features, it's time to start testing it.
Especially since our own use in CI is rather basic,
so it doesn't cover e.g. symlinks or non-YAML encodings.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: I51e113c7100ef6585260a562f2c8dd7a1ae643c8
Reviewed-on: https://cue.gerrithub.io/c/cue-lang/cue/+/1232052
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Paul Jolly <paul@myitcv.io>