[SIGMON-319] Tests for the QueryParams domain objects

Context

• story: https://its.cern.ch/jira/browse/SIGMON-261
• task: https://its.cern.ch/jira/browse/SIGMON-319

What was done

• the logic that merges the QueryParams objects improved. (signals with the same triplets are grouped together etc)

TODO

• the whole story needs to be finished

QA

• sonar: http://sonar/dashboard?branch=SIGMON-319_query_params_test&id=lhc-sm-api
• code was unit tested
• acceptance tests will be written in https://its.cern.ch/jira/browse/SIGMON-299 (the QueryBuilder will use the new code)

Review objectives

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