Parses ray tracing shader entry point specification string in one of the following formats: 1) Verbatim single entry point name, e.g. "MainRGS" 2) Complex entry point for ray tracing hit group shaders: a) "closesthit=MainCHS" b) "closesthit=MainCHS anyhit=MainAHS" c) "closesthit=MainCHS anyhit=MainAHS intersection=MainIS" d) "closesthit=MainCHS intersection=MainIS" NOTE: closesthit attribute must always be provided for complex hit group entry points