Add a CMake option to build RDC library only

When RDC are only used as the libraries, the user can choose not to build
the rdci and rdcd, which will remove the dependencies to the gRPC and protoc.
The -DBUILD_STANDALONE=off should be pass to the cmake.
* Change README.md for the instructions.
* Move the python_binding installation from client/CMakeLists.txt to CMakeLists.txt
  so that the RDC library only build will also install the folder.
* Change CMakeLists.txt and rdc_libs/CMakeLists.txt to build with gRPC only if
  the BUILD_STANDALONE is enabled.

Change-Id: If9cfe9fc298a83636d85fe352a311fe2fe041661


[ROCm/rdc commit: 105675aeeb]

projects/rdc/client/CMakeLists.txt

@@ -164,9 +164,6 @@ install(TARGETS ${CLIENT_LIB}
 install(DIRECTORY ${SOURCE_DIR}/authentication
              DESTINATION  ${RDC_CLIENT_INSTALL_PREFIX}/${RDC}
                                          COMPONENT ${CLIENT_COMPONENT})
-install(DIRECTORY ${SOURCE_DIR}/python_binding
-             DESTINATION  ${RDC_CLIENT_INSTALL_PREFIX}/${RDC}
-                                         COMPONENT ${CLIENT_COMPONENT})
 
 # Generate Doxygen documentation for client api manual
 find_package(Doxygen)