This makes handling linker errors on Windows related to the protobuf
sources easier to handle.

Adding the grpc-generated sources to the executable of each test fixes
the protobuf-related linker errors on Windows.

- add generated protobuf source directory to global include folders

On Windows this does not compile without. On Linux, it should not hurt.

Linking against caosdb should achieve the same.

This is experimental.

Add vcpkg support

See merge request !53

This was necessary for gcc prior to 9.1 and is no longer necessary.

This fixes issue #88 on Win32

We're not compatible with boost>=1.83 due to deprecation of string_file

boost::beast is header-only, so find_package will fail.

to_string method of boost::json::string_view was removed.

libcaosdb is not compatible with boost 1.86.0, so we go down with vcpkg's baseline version.

- include manual copy of grpc-cpp-plugin

- Only use required components of boost
- Link automatically to ${Boost_LIBRARIES}