Resolve "snake case all data and services"

Description

This renames all data and services in snake_case.

The underlying objective was to put in snake_case most things in XML files. Thus extension points were renamed as well. Doing this, the AppConfigManager was extracted from sight::service to a new library sight::app. To obtain the symmetry, sight::module::appXml was renamed to sight::module::app.

Closes #1171 (closed)

How to test it?

CI pipeline result should be enough.