Joint Rails - Add GM compat

[lambdatiger]

When merged this pull request will:

• Add GM RIS mount weapons to JR
• Add GM AK dovetail mounts to JR
• Add a JR class for RPG-7 optics and add GM's to it
  • This may be less useful due to model differences, but they added their own and I thought it would be better if it was easier to add
• Added GM optics to SVD JR
  • This could stay or go, they're attached slightly higher than some other mod's dovetails

This PR fixes CBA overriding the GM team's attempts to add their optics to vanilla weapons. Another PR will follow (soon TM) adding JR to GM weapons.