Note that there are currently some differences from the Thing Model published by the W3C including content types (no support for application/td+json and application/problem+json) and response codes. Also, event affordances and search affordances are not currently implemented.
Builds on #3147 so will need rebasing once that lands.
Closes #2927.
This PR enables the gateway to serve a top level W3C WoT Thing Description for the gateway itself, which describes the parts of the W3C WoT Directory Service API which the gateway currently exposes.
Note that there are currently some differences from the Thing Model published by the W3C including content types (no support for
application/td+jsonandapplication/problem+json) and response codes. Also, event affordances and search affordances are not currently implemented.