Gunmod slot audit on wooden stock longguns

[TheShadowFerret]

Summary

Bugfixes "Wooden stock longguns require mounts to use gunmods"

Purpose of change

Stocks were strangely mostly left alone when gunmod mounts were added, allowing single-piece wooden stocks that generally only interchange with the same rifle family to be replaced for folders and adjustable stocks without modifications. Also, #58936 can't be used on all guns that it should.

Describe the solution

Move over wooden stocked longguns to use stock mounts, in addition to checking if the RL gun has a mounting system by default for those modslots.

Describe alternatives you've considered

Taking away less modslots on the guns by only looking at the stock, but I am mean thorough so I won't :D

Testing

Bubba'd precious historical firearms

Additional context

Increased difficulty of getting tacticool weapon setups is noted, but now that nested_guns.json exists for every gun available it is much easier to now add a rare chance for someone to have already modified the gun to have mounts on it.

I left sights alone if the weapon is drilled for ring mounts or has any form of native mounting.