[GR-7747] Improve performance of package test analyzer.

...acle/truffle/r/test/packages/analyzer/FileTreeWalker.java

.../com/oracle/truffle/r/test/packages/analyzer/PTAMain.java

.../com/oracle/truffle/r/test/packages/analyzer/Problem.java

...t/packages/analyzer/detectors/ConfigureErrorDetector.java

...kages/analyzer/detectors/InstallationProblemDetector.java

...le/r/test/packages/analyzer/detectors/RErrorDetector.java

...t/packages/analyzer/detectors/RInternalErrorDetector.java

.../r/test/packages/analyzer/detectors/SegfaultDetector.java

...ackages/analyzer/detectors/SymbolLookupErrorDetector.java

...analyzer/detectors/UnsupportedSpecializationDetector.java

...cle/truffle/r/test/packages/analyzer/dump/HTMLDumper.java