Create default monorepo

Following work done for https://github.com/Jahia/jahia-private/issues/3448, the following codebases should be brought together:

- https://github.com/Jahia/contentRetrieval
- https://github.com/Jahia/default
- https://github.com/Jahia/jquery
- https://github.com/Jahia/search
- https://github.com/Jahia/templates-system

