Fix test Errors, and use junit 5 assertions.

...t/java/org/jastadd/ros2rag/tests/DefaultOnlyReadTest.java

.../java/org/jastadd/ros2rag/tests/DefaultOnlyWriteTest.java

...tests/src/test/java/org/jastadd/ros2rag/tests/Errors.java

.../src/test/java/org/jastadd/ros2rag/tests/ExampleTest.java

.../test/java/org/jastadd/ros2rag/tests/Read1Write2Test.java

.../test/java/org/jastadd/ros2rag/tests/Read2Write1Test.java

...src/test/java/org/jastadd/ros2rag/tests/RosToRagTest.java