Validation result `open` not supported

Describe the bug

With the current implementation, rules evaluate to either pass or fail but not to open:

dgc-certlogic-android/engine/src/main/java/dgca/verifier/app/engine/DefaultCertLogicEngine.kt

Lines 70 to 73 in d9bd513

    
           val res = when { 
        
               isValid -> Result.PASSED 
        
               else -> Result.FAIL 
        
           }

Expected behaviour

Determine open based on the EngineVersion (see also eu-digital-green-certificates/dgc-certlogic-ios#6)
use open is the validation fails for technical reason (see also eu-digital-green-certificates/dgc-certlogic-ios#5)

Steps to reproduce the issue

look at the code

Technical details

n/a

Possible Fix

see expected behavior

Additional context

n/a

PR: #14

I think this is not quite right yet, but I'm closing this in favor of #28

	val res = when {
	isValid -> Result.PASSED
	else -> Result.FAIL
	}