[GR-5543] Reusing temporary vectors in conversion builtins.

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

...src/com/oracle/truffle/r/nodes/builtin/base/AsDouble.java

...rc/com/oracle/truffle/r/nodes/builtin/base/AsInteger.java

...rc/com/oracle/truffle/r/nodes/builtin/base/AsLogical.java

...in/src/com/oracle/truffle/r/nodes/builtin/base/AsRaw.java

...acle/truffle/r/nodes/function/opt/ReuseTemporaryNode.java

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

...acle/truffle/r/test/builtins/TestBuiltin_ascharacter.java

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

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

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

...com/oracle/truffle/r/test/builtins/TestBuiltin_asraw.java