Add generated GRPC sources to ccaosdb library (partially addresses #34)

This fixes error LNK2019: unresolved external symbol errors using msvc

CMakeLists.txt

@@ -199,7 +199,7 @@ target_include_directories(caosdb SYSTEM PUBLIC
     ${CONAN_INCLUDE_DIRS}
 )
 
-add_library(ccaosdb SHARED src/ccaosdb.cpp)
+add_library(ccaosdb SHARED src/ccaosdb.cpp ${GRPC_GENERATED})
 
 IF (WIN32)
     target_link_libraries(ccaosdb