Introduce Text query embedding method

[albertisfu]

This would be the last pice related to the embedding microservice project.

• This task consist to create a method that can be called within the Case Law semantic search as a previous step to send the query to ES.
• It'll be as simple as calling the embedding microservice synchronously and using the response to build the semantic ES query.
  This method should be called for either the frontend and the Search API if we're also considering making semantic search available via the API.
• This task could also include creating the semantic query using the query embedding and adding tests to ensure that semantic queries work properly.

The UI and additional components for making semantic search available to users are not considered here. Should they be? @mlissner

[mlissner]

and the Search API

We'll actually be developing the API first this time. Doing the UI work will come later, hopefully after the new version of the site is launched.