third_party/json and docker context size

[niklas88]

The nlohmann/json submodule is quite large due to including a large test suite. We actually only need a single file json/json.hpp from this repository (+ CMakeLists.txt for setting up the include) but we still get the full size of the repository. This also blows the docker build context to 477 MB.

Sadly there is currently no official git repository without the test suit (see here). So the easiest solution would probably be to include the header + a minimal CMakeLists.txt directly in the thid_party/json folder.

[joka921]

You are so very right. This is especially bad for dockering etc.
Actually I think we do not need the CMakeLists.txt since we can just add the include to our main CMakeLists.txt (that also is the way it is currently done).

The only problem is keeping track of versions, do you have any idea other than remembering to check every now and then for new releases etc?

[niklas88]

Not really but then again we would have to check manually for a submodule as well.