announce tus feature in Providerinfo

[butonic]

Add tus feature and version to https://cs3org.github.io/cs3apis/#cs3.storage.registry.v1beta1.ProviderInfo

To properly handle [crappy proxies] we also need to be able to return the chunk size: tus/tus-resumable-upload-protocol#93

[butonic]

for now we can add this to the ocs capabilities, but in the future we would like to expose the different storage capabilities in a list per storage. quota is another property that is not the same for the whole instance but per storage.