restore AI switching to AOE weapons

[Keshash]

Additions

Describe new functionality added by your code, e.g.

• Re-adds Karim's old code for AI switching to grenades/launchers, shooting once at the center of enemy swarm, then switching back to main gun
• fixes a bug where AOE weapons that can't ignore blocked LoS (rpg, law) were unable to shoot at enemies behind cover. If pawn has such weapon, they will target the enemy pawn instead of ground between enemies.
• fixes a NRE which presumably got this code commented out 1 year ago.
• I've removed a significant chunk of checks and target calculations, making it instead simply target the current enemy with the grenade to improve performance.

References

Links to the associated issues or other related pull requests, e.g.

• Undoes this commit

Reasoning

Why did you choose to implement things this way, e.g.

• Enemies using grenades and launchers makes the game more interesting. We should give them more grenades in a future xml-only pr

Alternatives

Describe alternative implementations you have considered, e.g.

• Rewrite the target selection logic in such a way that wouldn't harm performance as much.
• Ideally, would also implement this for: underbarrels, emp usage, firefoam

Testing

Check tests you have performed:

• Compiles without warnings
• Game runs without errors
• (For compatibility patches) ...with and without patched mod loaded
• Playtested a colony
  tested devmode raids only so far

[github-actions]

You can download the rebuilt assembly for this PR here: https://combatextended.lp-programming.com/CombatExtended-16840123609.zip

[github-actions]

You can download the rebuilt assembly for this PR here: https://combatextended.lp-programming.com/CombatExtended-16840204395.zip

[github-actions]

You can download the rebuilt assembly for this PR here: https://combatextended.lp-programming.com/CombatExtended-16851835218.zip

[github-actions]

You can download the rebuilt assembly for this PR here: https://combatextended.lp-programming.com/CombatExtended-16852300872.zip

[Keshash]

I've tested it in more sterile conditions, 1 pawn attacking, measured at 10 calls. here's what I got on performance. Would like to know your opinions on if this is acceptable performance or should I ditch this endeavor of reviving weapon switching.
Average per call seems to yield unconsistent result, but max per frame was more or less consistent in all tests.

Without AoE switching:
0.126 ms max per frame, 231 average per call

With cut down AoE switching:
0.185 ms max per frame, 217 average per call

With original implementation of AoE switching:
0.238 ms max per frame, 249 average per call

Without:

With:

Old: