Provide default props file for use by mods

[CptMoore]

Topics Props:

• BT libs vs injectors (vs netstandard2.0 libs)?
  • provide variants: ModTekBattleTechMod.props, ModTekInjector.props(, ModTekNetStandard.props)
  • or: ModTemplate.props, InjectorTemplate.props
  • (dont repeat modtek, template name good if too much in props)
• ModTek provided: HarmonyX, Mono.Cecil
  • Does not matter what the mod wants, its the mod pack that decides the actual version anyway
• Compile time only: Kraf.Publicizer and PolySharp, LangVersion
  • Might hurt to pre-set in case a mod is using newer than installed BTA/RT
  • Maybe version them? Like ModTekCSharp13.props