Update @context URLs, add response contentType workaround

[JKRhb]

This PR updates the @context URLs included in the directory's TM/TD in anticipation of w3c/wot-discovery#471 and applies the workaround added in w3c/wot-discovery#469 to the ThingDescriptionBuilderService by inserting application/x-empty as a contentType for response objects where the field absent.

Combined, these changes result in a TD for the Directory that passes validation against the latest JSON Schema document provided in the TD repository :)

[JKRhb]

Needed to update two dependencies and create another workaround in 8f0b128 to get the TD instantiation to actually work again. Seems to me like a bug has appeared in the td-tools package that modifies the input TM, which apparently has not happened before 🤔

[relu91]

Hi Jan! As always thank you really much for contributing to Zion. The changes look good, but I checked the difference in package-lock and saw changes in unrelated packages like Fastify. Do you have an idea why this is happening? Can you try to narrow down the changes to only node-wot and wot-thing-description-types packages?

[JKRhb]

Hi Cristiano, thank you for the feedback! Sure, I will check again and try to narrow down the changes :)

[JKRhb]

With the latest push, I managed to trim down the changes in the package-lock.json file by a lot. However, for some reason, the tests are now failing since the td-tools apparently does not include the latest fixes for the TM JSON schema 🤔 We may need to put this PR on hold then until version 0.8.6 of the td-tools package with the updated schema has been released.

[relu91]

Ok, in my understanding we are going to release 0.8.6 very soon. I'll check if we get the green light once it will be published!

[JKRhb]

The new td-tools release actually solved the problem 🎉

[JKRhb]

I am now wondering: Should we wait for w3c/wot-discovery#471? Or would it be fine to already merge this PR?

[relu91]

I ok for merging this right now, I'm confident that the linked PR in the discovery repo will be merged soon.

[JKRhb]

w3c/wot-discovery#471 has now been merged by the way, so the spec is not a potential blocker anymore :)

[relu91]

Talked offline with @hyperloris, he was a little bit uncomfortable with merging a PR with TODOs in it. I agree but those TODOs are reasonable and they can be tracked in issues (as suggested by @hyperloris himself). Therefore, I'm forcing the merging of the PR without waiting for his formal approval. Later on, I'll open the tracking issues.