test: query: policy: combined-pinning-filters: added tests for multi-package records
lib: internal: pininfo: loadFirstPinRecordLine: refactoring: avoided FORIT
lib: internal: pininfo: loadFirstPinRecordLine: tiny optimisation: avoided constructing std::string for package type check
lib: internal: pininfo: refactoring: new method 'loadReleaseConditions'
test: query: policy: pinning-by-release-properties: added tests for invalid release property letter