writeall and writemultiple are not conforming to the TD spec

[danielpeintner]

... writeall and writemultiple are not conforming to the TD spec. They do not seem to accept a single request to write into all the properties but as done in consumed-thing.ts, all of them has to be written separately.

Originally posted by @egekorkan in https://github.com/eclipse/thingweb.node-wot/issues/949#issuecomment-1508282901