restructure extract/replace nodes and convert to VectorAccess

...com/oracle/truffle/r/nodes/builtin/base/GetFunctions.java

...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

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

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

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

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

....r.nodes/src/com/oracle/truffle/r/nodes/objects/AsS4.java

...src/com/oracle/truffle/r/nodes/objects/GetS4DataSlot.java

....r.runtime/src/com/oracle/truffle/r/runtime/RRuntime.java