Remove triplestore -> jsonld dependency

Hello,

I'd want to start a Moleculer Semapps instance with just the `triplestore` service (just accessing database to do queries), but the triplestore service has an **undocumented** dependency to `jsonld` service, which has recursively dependencies to `api` service, and `ontologies` service. It would be nice to be able to start a database adapter without having to declare 3 others services, with api and port required.

The only reference to jsonld inside triplestore service is here: https://github.com/assemblee-virtuelle/semapps/blob/master/src/middleware/packages/triplestore/actions/insert.js#L35-L40

If I understand well, this serves to format RDF query from provided json object, and adding correctly prefixes from ontologies.

I don't know how we can manage to remove this dependency without breaking the feature, except make the jsonld service dependency optional and throw an error if we try to call it if not defined, or otherwise we can try to reimplement the logic of RDF conversion from jsonld service inside the triplestore service (but it's not so easy, as [it also manages a local cache](https://github.com/assemblee-virtuelle/semapps/blob/master/src/middleware/packages/jsonld/services/document-loader/index.js#L26-L46) and so...).

What do you think?

Start with src/middleware/packages/triplestore/actions/insert.js, especially the referenced jsonld call, and inspect src/middleware/packages/jsonld/services/document-loader/index.js for the cache behavior. Determine how the triplestore can run without the jsonld, api, and ontologies services while preserving RDF conversion and prefix handling; done means the dependency is removed or made safely optional without breaking existing queries.

Written by the indexing model from the issue text.