Redmine#3285: bundlesmatching() function with acceptance test

Finishing up https://cfengine.com/dev/issues/3285

The namespace is always prepended so it's not ambiguous.

The acceptance test show that dynamic call sequences with `usebundle` works with the namespace prefixed, but dynamic call bundlesequences don't work (the namespace is not accepted).  The latter care is in https://github.com/tzz/core/commit/b3a7bcbf785e0d127f8dd2580d04d8170d7d6056 as `01_vars/02_functions/staging/bundlesmatching_dynamicbundlesequence.cf`.

Will add documentation as soon as this is accepted.