Further consistency updates for shotshells

[chaosvolt]

Summary

SUMMARY: Balance "Give shotshells baseline dispersion, consistency updates for scrap shells, paper shot, birdshot"

Purpose of change

Consistency updates for some 12 gauge and 20 gauge shot loads.

Describe the solution

1. Changed scrap shot's damage to be 0.75x that of 00 shot instead of 0.6x. This makes it correctly be more damaging (60) than birdshot is currently.
2. Changed birdshot to not override default dispersion to 1000. It doesn't matter statistically since it still uses AoE effects, but it does make it more visually consistent and makes it less hassle to tweak other dispersion values.
3. Gave 00 shot a baseline dispersion of 20. This makes the increased dispersion of black powder loads actually visible.
4. Set scrap shot to have 60 dispersion, to make its stated poor accuracy evident. Also set it to have an armor multiple in between 00 shot and birdshot.
5. Added baseline 20 dispersion to paper shot abstract to distinguish from 00 shot changes.
6. Set paper birdshot to have an armor modifier of 3.0 like regular birdshot does.
7. Set pyrotechnic 20ga cartridge to have heat-type damage instead of ballistic, matching how dragon's breath is balanced. 24 damage, matching how 12 gauge dragon's breath is 3/8ths that of 00 shot.

Describe alternatives you've considered

Nerfing 00 shot a bit more. Eh, it's beefy but works okay in this role I figure, especially since the armor multipliers do compensate for that somewhat. Only really makes it just hard to feel consistent with respect to earlier ammo balance efforts.

Testing

1. Checked affected file for syntax and lint errors.
2. Load-tested and checked that stats on affected items show expected values.

Additional context