Implement the `function` builtin

...rc/com/oracle/truffle/r/engine/RRuntimeASTAccessImpl.java

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

...tin/src/com/oracle/truffle/r/nodes/builtin/base/Call.java

...e/truffle/r/nodes/builtin/base/infix/FunctionBuiltin.java

...e.r.nodes/src/com/oracle/truffle/r/nodes/RASTBuilder.java

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

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

.../src/com/oracle/truffle/r/runtime/nodes/RCodeBuilder.java

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

...om/oracle/truffle/r/test/builtins/TestBuiltin_ascall.java

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