(cherry picked from commit f9e555a0)

This is a preparation for CI improvements which will enable usage of the
crate name variable to detect changes inside specific paths, allowing
to conditionally run tests only if a specific crate is affected. In
addition it removes some confusion about the meaning of folder names,
e.g. each signaling module can now be identified by the corresponding
path prefix.

Closes: #305

cargo doc --workspace --no-deps reported some unlinked, errornous
docs. This commit fixes them.

Modules are now crates separate from the controller. This allows for adding
features in the future without having the add them to the main repository.

Fix documentation where rustdoc warned.

Update dependencies where needed.

implemented:

- basic scheduling depending on selection strategy
- moderator commands to edit the automod lists (allow/playlist) while running
  and forcibly reselect the speaker

missing:

- time_limit
- pause_time
- consider_hand_raise - hand raise feature is missing completely

Co-authored-by: Rudi Floren <r.floren@heinlein-video.de>

- Resolve problem which required PeerFrontendData to have a Deserialize bound
- Remove redis storage abstractions which was very limited in its capabilities
  to allow modules to define their own operations and keys
- Use r3dlock to guard participant list and therefore runner destroy

The r3dlock crate tests require a redis instance running

Co-Authored-By: Konstantin Baltruschat <k.baltruschat@heinlein-video.de>