Support S4 objects with .Data or .xData in subscribe operations

...ruffle/r/nodes/access/vector/CachedExtractVectorNode.java

...ruffle/r/nodes/access/vector/CachedReplaceVectorNode.java

...racle/truffle/r/nodes/access/vector/CachedVectorNode.java

...le/truffle/r/nodes/access/vector/ExtractS4ObjectNode.java

...le/truffle/r/nodes/access/vector/ReplaceS4ObjectNode.java

...acle/truffle/r/nodes/access/vector/ReplaceVectorNode.java

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

...le.r.runtime/src/com/oracle/truffle/r/runtime/RError.java

...est/src/com/oracle/truffle/r/test/ExpectedTestOutput.test

...uffle.r.test/src/com/oracle/truffle/r/test/S4/TestS4.java