Redo 81mm as generic shell

[Safairette]

Additions

• Added a new mod extension that can override labels, descriptions and jobStrings for ThingDefs, RecipeDefs and AmmoSetDefs in generic mode, where applicable.
• Added missing shell translations for Russian translation.

Changes

• Changed 81mm mortar to act as generic base for other small shells.
• Removed previous generic shell.
• Renamed the generic file to fit the changes.

Reasoning

• There's more hardcoded references than initially expected.
• A mod extension is still available for patches or translations, as opposed to a conditional patch op.
• Doesn't separate the ammo data into separate files.

Alternatives

• Go with conditional patching.
• Patch more references to fit the 'normal' generic scheme.

Testing

Check tests you have performed:

• Compiles without warnings
• Game runs without errors
• Playtested a colony (specify how long)

[github-actions]

You can download the rebuilt assembly for this PR here: https://combatextended.lp-programming.com/CombatExtended-12436286594.zip

[github-actions]

You can download the rebuilt assembly for this PR here: https://combatextended.lp-programming.com/CombatExtended-12436318377.zip

[github-actions]

You can download the rebuilt assembly for this PR here: https://combatextended.lp-programming.com/CombatExtended-12458817611.zip