Replace ParamFetcher with model classes
Description
Some API endpoints are using the ParamFetcher class for HTTP body parameters. Instead, we can replace it with model classes like in !2421 (merged) and let Symfony do the mapping.
To find all instances, search for ParamFetcher
in src/RestApi: https://gitlab.com/search?group_id=761945&project_id=1454647&scope=blobs&search=ParamFetcher&language%5B%5D=PHP
Edited by Alex