[GR-2798] Implement ATTRIB in StdUpCallsRFFI.

...oracle/truffle/r/ffi/impl/common/JavaUpCallsRFFIImpl.java

...cle/truffle/r/ffi/impl/common/TracingUpCallsRFFIImpl.java

...com/oracle/truffle/r/ffi/impl/upcalls/StdUpCallsRFFI.java

...e.truffle.r.native/fficall/src/common/rffi_upcallsindex.h

com.oracle.truffle.r.native/fficall/src/jni/Rinternals.c

...fle.r.test.native/packages/testrffi/testrffi/R/testrffi.R

...uffle.r.test.native/packages/testrffi/testrffi/src/init.c

...e.r.test.native/packages/testrffi/testrffi/src/testrffi.c

...e.r.test.native/packages/testrffi/testrffi/src/testrffi.h

...est.native/packages/testrffi/testrffi/tests/simpleTests.R