[SIGMON-297] Metadata Resolver

Context

• task: https://its.cern.ch/jira/browse/SIGMON-297

What was done

• resolver.py created

TODO

• QueryBuilder should use this code

QA

• http://sonar/dashboard?branch=SIGMON-297_metadata_resolver&id=lhc-sm-api
• code was tested (the coverage of resolver.py is _)

Review objectives

• assessment of code functionality
• assessment of code quality
• identifying potential refactorings / logic common to other projects
• knowledge sharing