[GR-3365] Remove FastR-specific SEXPTYPE entries.

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

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

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

...ntime/src/com/oracle/truffle/r/runtime/gnur/SEXPTYPE.java

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

...oracle/truffle/r/test/builtins/TestBuiltin_serialize.java

...acle/truffle/r/test/builtins/TestBuiltin_unserialize.java

...m/oracle/truffle/r/test/library/base/TestConnections.java