Using getPartialTDs() from thing-model tools

We are not using https://github.com/eclipse-thingweb/td-tools/blob/main/node/thing-model/src/tm-helpers.ts#L164 which helps with resolving links and also getting the TD. It returns multiple TDs to take https://w3c.github.io/wot-thing-description/#thing-model-composition into account but we can always return the 1st item if we know that the TM is not linking to other TMs.