C++/Go: Update gRPC related code to work with gRPC 1.3+ (#4305)

* Don't fail the build on unused parameters

gRPC headers have unused parameters so this breaks the test build.

* Pull in updated compiler files from gRPC

There have been some API breaks in gRPC lately. This commit
pulls in the most recent version of the files in this repo
that are just copied from gRPC.

* Modify the gRPC files so that they can work with Flatbuffers

The files taken from gRPC do not work out-of-the-box with Flatbuffers.
This commit modifies them so that they work. Hopefully this commit
will be able to serve as a guide or maybe even be cherry-picked on
top of new versions of those files as newer versions from gRPC are
pulled in.

* Adjust the rest of Flatbuffers to work with the new gRPC

* Change idl_gen_grpc.cpp to work with the new API
* Add missing #include in flatbuffers/grpc.h
* Run tests/generate_code.sh and check in the results
* Don't link with grpc++_unsecure and (secure) grpc. That's just weird

* Revert unrelated JS/TS test changes

* Simplify compiler/config.h

There is no need to import this file from gRPC. In fact, it probably
makes sense to not do so, since it seems to be intended to have
project specific configuration in it.

* Don't emit C++ types in the Go gRPC code generator

* Don't emit C++ #includes in generated gRPC code

Before this PR, there was a Go-specific additional_includes method
in schema_interface.h, which is shared with the gRPC repo. The
additional parameter to FlatBufFile in idl_gen_grpc.cpp makes that
unnecessary, which means we need less Flatbuffer-specific changes
in gRPC.

grpc/src/compiler/cpp_generator.h

@@ -41,8 +41,20 @@
 #include <memory>
 #include <vector>
 
+#include "src/compiler/config.h"
 #include "src/compiler/schema_interface.h"
 
+#ifndef GRPC_CUSTOM_STRING
+#include <string>
+#define GRPC_CUSTOM_STRING std::string
+#endif
+
+namespace grpc {
+
+typedef GRPC_CUSTOM_STRING string;
+
+}  // namespace grpc
+
 namespace grpc_cpp_generator {
 
 // Contains all the parameters that are parsed from the command line.
@@ -53,31 +65,73 @@ struct Parameters {
   bool use_system_headers;
   // Prefix to any grpc include
   grpc::string grpc_search_path;
+  // Generate GMOCK code to facilitate unit testing.
+  bool generate_mock_code;
 };
 
 // Return the prologue of the generated header file.
-grpc::string GetHeaderPrologue(grpc_generator::File *file, const Parameters &params);
+grpc::string GetHeaderPrologue(grpc_generator::File *file,
+                               const Parameters &params);
 
 // Return the includes needed for generated header file.
-grpc::string GetHeaderIncludes(grpc_generator::File *file, const Parameters &params);
+grpc::string GetHeaderIncludes(grpc_generator::File *file,
+                               const Parameters &params);
 
 // Return the includes needed for generated source file.
-grpc::string GetSourceIncludes(grpc_generator::File *file, const Parameters &params);
+grpc::string GetSourceIncludes(grpc_generator::File *file,
+                               const Parameters &params);
 
 // Return the epilogue of the generated header file.
-grpc::string GetHeaderEpilogue(grpc_generator::File *file, const Parameters &params);
+grpc::string GetHeaderEpilogue(grpc_generator::File *file,
+                               const Parameters &params);
 
 // Return the prologue of the generated source file.
-grpc::string GetSourcePrologue(grpc_generator::File *file, const Parameters &params);
+grpc::string GetSourcePrologue(grpc_generator::File *file,
+                               const Parameters &params);
 
 // Return the services for generated header file.
-grpc::string GetHeaderServices(grpc_generator::File *file, const Parameters &params);
+grpc::string GetHeaderServices(grpc_generator::File *file,
+                               const Parameters &params);
 
 // Return the services for generated source file.
-grpc::string GetSourceServices(grpc_generator::File *file, const Parameters &params);
+grpc::string GetSourceServices(grpc_generator::File *file,
+                               const Parameters &params);
 
 // Return the epilogue of the generated source file.
-grpc::string GetSourceEpilogue(grpc_generator::File *file, const Parameters &params);
+grpc::string GetSourceEpilogue(grpc_generator::File *file,
+                               const Parameters &params);
+
+// Return the prologue of the generated mock file.
+grpc::string GetMockPrologue(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the includes needed for generated mock file.
+grpc::string GetMockIncludes(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the services for generated mock file.
+grpc::string GetMockServices(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the epilogue of generated mock file.
+grpc::string GetMockEpilogue(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the prologue of the generated mock file.
+grpc::string GetMockPrologue(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the includes needed for generated mock file.
+grpc::string GetMockIncludes(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the services for generated mock file.
+grpc::string GetMockServices(grpc_generator::File *file,
+                             const Parameters &params);
+
+// Return the epilogue of generated mock file.
+grpc::string GetMockEpilogue(grpc_generator::File *file,
+                             const Parameters &params);
 
 }  // namespace grpc_cpp_generator