Introduce Tracking CA flags

Now that the InDet/ITk/Tracking CA configurations have been reorganised, it becomes easier to identify flags relevant for Tracking reconstruction from those related to the ID/ITk detector configurations. This MR aims thus at introducing a new category of reco flags labelled under Tracking.

The current Acts standalone flags are also planned to be migrated under Tracking.Acts. Ultimately they could move under Tracking as soon as the corresponding algorithms are commissioned.

Comments are very welcome.

To keep the review manageable, flags will be migrated progressively, in different MRs.

(see ATLASRECTS-7467)

FYI @pagessin @lgagnon @ncalace @cvarni @sroe @goetz @nstyles @tadej @christos