Merge pull request #23604 from dkurt:dnn_no_protobuf

Build DNN without Protobuf

DNN module can be built without Protobuf for Darknet, TFLite, OpenVINO, Torch (not PyTorch) models.

```
cmake \
    -DCMAKE_BUILD_TYPE=Release \
    -DBUILD_LIST=dnn \
    -DWITH_PROTOBUF=OFF \
    -DWITH_OPENCL=OFF

7.1M    lib/libopencv_dnn.so.4.7.0
```


```
cmake \
    -DCMAKE_BUILD_TYPE=Release \
    -DBUILD_LIST=dnn \
    -DWITH_OPENCL=OFF

3.9M    lib/libopencv_dnn.so.4.7.0
```

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/dnn/src/init.cpp

@@ -42,7 +42,7 @@
 #include "precomp.hpp"
 #include <opencv2/dnn/layer.details.hpp>
 
-#if !defined(BUILD_PLUGIN)
+#if defined(HAVE_PROTOBUF) && !defined(BUILD_PLUGIN)
 #include <google/protobuf/stubs/common.h>
 #endif
 
@@ -60,7 +60,7 @@ Mutex& getInitializationMutex()
 // force initialization (single-threaded environment)
 Mutex* __initialization_mutex_initializer = &getInitializationMutex();
 
-#if !defined(BUILD_PLUGIN)
+#if defined(HAVE_PROTOBUF) && !defined(BUILD_PLUGIN)
 namespace {
 using namespace google::protobuf;
 class ProtobufShutdown {
@@ -80,7 +80,7 @@ void initializeLayerFactory()
 {
     CV_TRACE_FUNCTION();
 
-#if !defined(BUILD_PLUGIN)
+#if defined(HAVE_PROTOBUF) && !defined(BUILD_PLUGIN)
     static ProtobufShutdown protobufShutdown; CV_UNUSED(protobufShutdown);
 #endif