Unit tests: CPPUNIT -> Catch2: str

alib2str/test-src/automaton/AutomatonTest.cpp

alib2str/test-src/automaton/AutomatonTest.h

alib2str/test-src/container/ContainerTest.cpp

alib2str/test-src/container/ContainerTest.h

alib2str/test-src/grammar/GrammarTest.cpp

alib2str/test-src/grammar/GrammarTest.h

alib2str/test-src/main.cpp

alib2str/test-src/object/LabelTest.cpp

alib2str/test-src/object/LabelTest.h

alib2str/test-src/object/ObjectTest.cpp

alib2str/test-src/object/ObjectTest.h

alib2str/test-src/object/SymbolTest.cpp

alib2str/test-src/object/SymbolTest.h

alib2str/test-src/regexp/RegExpTest.cpp

alib2str/test-src/regexp/RegExpTest.h

alib2str/test-src/string/StringTest.cpp

alib2str/test-src/string/StringTest.h

alib2str/test-src/tree/TreeTest.cpp

alib2str/test-src/tree/TreeTest.h