implicit rule setup by the host (restroom-mw)

[jaromil]

Steps to reproduce

The rule directive in Zenroom is designed to be set by the calling host to setup the behavior of the VM and does not need to be exposed to the users of the host.

Therefore this:

# Always use 'Rule caller restroom-mw' when using Restroom
Rule caller restroom-mw

Should not be necessary, restroom-mw should prefix this rule to the zencode before execution into the Zenroom VM