rename debug package to fastr

.../com/oracle/truffle/r/nodes/builtin/RBuiltinPackages.java

...le/truffle/r/nodes/builtin/fastr/FastRCompileBuiltin.java

...racle/truffle/r/nodes/builtin/fastr/FastRDumpBuiltin.java

...racle/truffle/r/nodes/builtin/fastr/FastRInfoBuiltin.java

...om/oracle/truffle/r/nodes/builtin/fastr/FastRPackage.java

...m/oracle/truffle/r/nodes/builtin/fastr/FastRSetField.java

...com/oracle/truffle/r/nodes/builtin/fastr/FastRSource.java

...racle/truffle/r/nodes/builtin/fastr/FastRTreeBuiltin.java

...cle/truffle/r/nodes/builtin/fastr/FastRTypeOfBuiltin.java

...racle/truffle/r/nodes/builtin/fastr/FastRUsePromises.java

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