cue/load: add test case for issue 3306
This adds a test case for using `cue/load.Config.PkgName` as `*`,
showing extra files and instances that should not be present.
This behavior will be fixed in a subsequent CL.
For #3306
Signed-off-by: Roger Peppe <rogpeppe@gmail.com>
Change-Id: Ibf19e020ecdfa58e6841d517f5fcf0282615504a
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1198685
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>