Sends the Spas-12 into retirement, Mossbergs divorce, and Benellis invade

[DoctorBoomstick]

Summary

Content "Adds three new Benelli semi-automatic shotguns, splits the Mossberg 500 Field and 500 Security, and retires the Spas-12."

Purpose of change

As I previously discussed in PR #71575, there are some guns in CDDA that, while very cool, are far too rare in the real world to ever be found within the environment the game simulates. These are weapons that, whether being foreign service rifles, banned destructive devices, or one of a number of other categories of guns, fell into the status of highly rare pieces that would, at best, come up once in a while during a several hundred-hour playthrough after having already played the game for several years. Last time, the patient slated for invasive surgery was the AK-74M assault rifle, and this round, it’s the Spas-12’s turn to go under the knife.
Apart from the crusade against aberrant guns, issue #71233 pointed out that the Mossberg 500 Field and Security models of shotgun have identical stats, despite the former being described as possessing a 28-inch long barrel and the latter being an 18.5-inch configuration. This was due to both weapons being made variants of one another: fundamentally the same gun under the hood with a name and description change.
Lastly, I don’t enjoy removing something from the game without putting something back in. I happen to like Benellis. We happen to have one Benelli: the M1014. One plus one equals action had to urgently be taken to preserve the karmic balance of the CDDA gun world.

Describe the solution

In order, as previously discussed, in this PR, I have:

• Removed the Spas-12 variant from the Mossberg 590A1 combat shotgun and expunged any references to it from base game files. Sleep well, sweet prince. Go join Robert Muldoon in the big Jurassic Park in the sky.
• Replaced the Spas-12’s now empty variant position with the FN Self-Loading Police Mk I shotgun, following its recommendation as a suitable replacement candidate.
• Removed the Mossberg 500 Security from being a variant of the Mossberg 500 Field, whose barrel length has been increased to the required length of 28 inches.
• Added the Benelli M2 shotgun as a new gun.
• Added the Benelli Super Black Eagle 3 as a variant of the Benelli M2.
• Added the Benelli M2 Tactical as a new gun and made the Mossberg 500 Security a variant of it instead, where it fits a tad neater.
• Added the new guns to item groups as required.

Describe alternatives you've considered

I considered:

• Adding the Benelli M3, however, I was advised that it was likely too uncommon to include in the game, given our current criteria. No resident evil 3 shotgun, unfortunately, unless somebody can dig up some good hard numbers, which I haven’t been able to.
• Adding some of the new shotguns, the Benelli M2 Tactical in particular, as a possible spawn in police armouries and in related item groups, considering that I often hear of these shotguns being employed by law nforcement, However, considering my inability to ever come across hard sources that point towards the use of these guns by New England police, I must assume that this is simply hearsay, advertising nonsense, or antiquated information.
• Adding more Benelli shotguns in general. While I have grown a tad tired of picking up the same shotgun to kill a zombie, throwing it back in the same corner of the bedroom, and going silently about my business while feeling it look at me with its stupid face as we go through unsuccessful couple counselling after the romantic spark died several games ago, it is 0:30 in the morning. My lucidity is fleeing.

Testing

I loaded a local build of the game with the changes implemented and punched my way into several gun and hunting stores, literally, and observed that the new guns spawned correctly. I picked up said guns and committed factory disassembly upon various zombies with no issues. I tried to spawn in a Spas through the debug menu with no results.

Additional context

Thanks to @tenmillimaster for working up a shortlist of includable Benelli guns that make it past the amount requirement.

[tenmillimaster]

I halp!

[DenCheesecake]

Thank you! Please keep the weapon updates coming! :)