Remove use of nuts-node code

[woutslakhorst]

rely on client code generation from OAS. The current setup already confuses devs.

[stevenvegt]

Would like to know what the confusion was about. Generating the code locally instead of including it from the nuts-node repository might not fix the confusion.
Were they familiar with the oapi spec? Were they able to read the golang code? Did they follow the introduction manual? The names of the client lib follows roughly the operationIDs from the swagger spec, so i'm curious why that did was not enough.

Perhaps we should enable the swagger client on the nuts-node in development mode, so people can play with the api themselves? Like https://github.com/swaggo/echo-swagger ?

[woutslakhorst]

If the demo is also to be a blueprint and thus also give an estimate on the amount of work others will have to do, then it should also include the client code generation.