Putting the ingress point directly on one end of the FLOT means that AI
flights won't start searching and engaging targets until they reach that
point. If the front line has advanced toward the flight's departure
airfield, it might overfly targets on its way to the IP.
Instead, place an IP for CAS the same way we place any other IP. The AI
will fly to that and start searching from there.
This also:
* Removes the midpoint waypoint, since it didn't serve any real purpose
* Names the FLOT boundary waypoints for what they actually are
Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2231.
mypy struggles to prove this cast correct when there are two or'd
isinstance checks where both types coincidentally have properties of the
same name (but no defined protocol making that explicit). I'm not really
sure why mypy is happy with this in its current state, but it isn't
after a change I'm making.
All our isinstance use is a bit of an anti-pattern anyway, so extract a
method that exposes the data we care about.
The start/end times for tankers aren't actually used, so this could be
simplified even more, but that data _should_ be used.
Flights without a meaningful TOT make the code around startup time (and
other scheduling behaviors) unnecessarily complicated because they have
to handle unpredictable flight plans. We can simplify this by requiring
that all flight plans have a waypoint associated with their TOT. For
custom flight plans, we can just fall back to the takeoff waypoint. For
RTB flight plans (which are only synthetic flight plans injected for
aborted flights), we can use the abort point.
This also means that all flight plans now have, at the very least, a
departure waypoint. Deleting this waypoint is invalid even for custom
flights, so that's no a problem.
During package planning we don't care about the details of the flight
plan, just the layout (to check if the layout is threatened and we need
escorts). Splitting these will allow us to reduce the amount of work
that must be done in each loop of the planning phase, potentially
caching attempted flight plans between loops.
Split the oversized file into one per plan type. This also moves the
layout responsibility out of the oversized FlightPlanBuilder and into
each flight plan type file.
