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}

(not functional yet, only how it should work later on)

Resolve "EXTERN: Adapt to Conan 2"

See merge request !49

Merge branch 'f-73-extern-adapt-to-conan-2-0' of gitlab.indiscale.com:caosdb/src/caosdb-cpplib into f-73-extern-adapt-to-conan-2-0

See issue in setuptools https://github.com/pypa/setuptools/issues/4483

# Conflicts:
#   doc/Install_develop.rst

- exports_source had to be adjusted
- CMakeLists and conanfile.py of test_package is still broken