Implement Rf_coerceVector as upcall

...oracle.truffle.r.native/fficall/src/common/coerce_fastr.c

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

.../src/com/oracle/truffle/r/nodes/ffi/CoerceVectorNode.java

...src/com/oracle/truffle/r/nodes/ffi/FFIUpCallRootNode.java

...c/com/oracle/truffle/r/nodes/ffi/JavaUpCallsRFFIImpl.java

.../src/com/oracle/truffle/r/nodes/ffi/RFFIUpCallMethod.java

...om/oracle/truffle/r/nodes/ffi/TracingUpCallsRFFIImpl.java

.../src/com/oracle/truffle/r/runtime/ffi/StdUpCallsRFFI.java

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

.../oracle/truffle/r/test/rffi/TestRFFIPackageCoercions.java

...rc/com/oracle/truffle/r/test/rpackages/TestRPackages.java