nzchar and pmatch: converted to cast pipelines

...n/src/com/oracle/truffle/r/nodes/builtin/base/NZChar.java

...n/src/com/oracle/truffle/r/nodes/builtin/base/PMatch.java

...c/com/oracle/truffle/r/nodes/builtin/base/PathExpand.java

...m/oracle/truffle/r/nodes/casts/PredefMappersSamplers.java

...s/src/com/oracle/truffle/r/nodes/builtin/CastBuilder.java

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

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

...racle/truffle/r/test/builtins/TestBuiltin_pathexpand.java

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