Changes

Fix Classic Ascent with sliders fully left

It sometimes takes a few ticks before the base game updates the vessel's
situation. This means that `VerticalHeadingTo` will disable the
actuation controls during this time.

If the vessel switches from `VERTICAL_ASCENT` to `GRAVITY_TURN` before
the situation changes, the actuation controls never get re-enabled
(`VerticalHeadingTo` never gets called while, according to the game, the
vessel has lifted off). This can happen if the pitch start velocity is
very small, for example if the auto-turn velocity slider is all the way
to the left.

This change makes sure that the actuation controls also get enabled
properly while in the `GRAVITY_TURN` phase of flight, by enabling the
actuation controls at the same time as the axis controls in the
`AttitudeTo` method.

Fixes the root cause of the problem in #2025.
 (commit: 836cda7)