JBIDE-16313 - Replace AST Visitors with simpler code

Removed all implementations of ASTVisitor in the org.jboss.tools.ws.jaxrs.core.jdt package
Fixed a few JUnit tests
JBIDE-16005 : execute WS tests when hitting the Return key

Signed-off-by: Fred Bricon <fbricon@gmail.com>
JBIDE-16422 - Fixing sonar issues in RS (not WS) code

Fixing 'critical' issues plus a bunch of 'major' ones
Added more unit tests for edge cases (null args in method calls)