Support generic modules with server-side rendering

**Is your feature request related to a problem? Please describe.**
generic modules bring a lot of synchronization constraints, since they embed the audio rendering.

**Describe the solution you'd like**
Another kind of module should be introduced that uses the server-side rendering that was recently introduced for other modules. That way we keep the ease-of-configuration with simple configuration files, and get more rendering flexibility.

**Additional context**
Depending on the synthesizer, the format of the audio could vary, we'll have to read the meta-data to determine the encoding. For synthesizers that would emit raw data, we could use explicit configuration.

To be noted: some synthesizers' licence forbid this, we'll have to take care of it.

The issue names no files, tests, or entry points. Start by comparing the existing generic modules with modules that already use server-side rendering, then investigate how synthesizer metadata and explicit raw-data configuration should be represented. Done means generic modules can use server-side rendering while selecting the correct audio encoding and respecting synthesizer licensing constraints.

Written by the indexing model from the issue text.