Make use of ferals in more specialized monstergroups

[chaosvolt]

Summary

SUMMARY: Content "Add spawns of ferals into relevant specialized monstergroups"

Purpose of change

As promised, a followup on #2780

Describe the solution

1. Added chances of feral scientists, labsec, and mechanics showing up in GROUP_CENTRAL_LAB, GROUP_LAB, and GROUP_MICROLAB (with a delay for 9mm labsec ferals), and into GROUP_LAB_SURFACE after a general delay (increased for 9mm labsec ferals).
2. Added feral scientists and solders to GROUP_LAB_FEMA with a delay.
3. Added feral soldiers to GROUP_MIL_WEAK and GROUP_MIL_BASE with a delay, and into GROUP_MIL_STRONG with no delay.
4. Added feral mechanics to GROUP_INDUSTRIAL_CENTER.
5. Added feral survivalists, preppers, and militia to GROUP_POLICE, GROUP_PREPPER_HOUSE, GROUP_PHARM, GROUP_ELECTRO, and GROUP_GROCERY with elevated delays (and especially small weights for the shop locations). Most of these being to inject crazed survivors who eventually get attracted to potential targets for looting (or just sheltered survivors becoming lost in the sauce, in the case of GROUP_PREPPER_HOUSE).

Describe alternatives you've considered

1. Adding a monstergroup specifically for gun store zeds, with an elevated chance of spawning gun-toting/survivalist ferals and survivor zombies.
2. Setting it so increased spawns of survivor zombies also filter into locations commonly targeted by feral preppers.

Testing

1. Checked affected files for syntax and lint errors.
2. Load-tested in compiled build.

Additional context

[Firestorm01X2]

Ready