[gameplay] Update siege techs.
A23 siege techs were rarely used. This:
- Lowers the cost of the attack tech slightly.
- Remove the cost techs which were not very useful or interesting.
- Rework the armor tech into a Health bonus
- Introduces a tech to pack/unpack faster.
Patch By: borg-
Accepted By: Feldfeld
Differential Revision: https://code.wildfiregames.com/D2878