rewritten the main test infrastructure to work with org.graalvm.polyglot.Engine/Context

.../truffle/r/nodes/access/vector/ExtractVectorNodeTest.java

.../truffle/r/nodes/access/vector/ReplaceVectorNodeTest.java

.../truffle/r/nodes/access/vector/StringCompareNodeTest.java

...e/truffle/r/nodes/access/vector/StringSearchNodeTest.java

....test/src/com/oracle/truffle/r/nodes/casts/TestCasts.java

...oracle/truffle/r/nodes/test/BinaryArithmeticNodeTest.java

...om/oracle/truffle/r/nodes/test/BinaryBooleanNodeTest.java

.../src/com/oracle/truffle/r/nodes/test/ChimneySweeping.java

...com/oracle/truffle/r/nodes/test/DefaultArgsExtractor.java

.../src/com/oracle/truffle/r/nodes/test/SpecialCallTest.java

...es.test/src/com/oracle/truffle/r/nodes/test/TestBase.java

.../oracle/truffle/r/nodes/test/UnaryArithmeticNodeTest.java

...me/src/com/oracle/truffle/r/runtime/context/RContext.java

...ruffle.r.test/src/com/oracle/truffle/r/test/TestBase.java

.../oracle/truffle/r/test/engine/interop/AbstractMRTest.java

...le/truffle/r/test/engine/interop/ActiveBindingMRTest.java

.../com/oracle/truffle/r/test/engine/interop/ListMRTest.java

...ffle/r/test/engine/interop/RArgsValuesAndNamesMRTest.java

...cle/truffle/r/test/engine/interop/REnvironmentMRTest.java

...oracle/truffle/r/test/engine/interop/RFunctionMRTest.java