Minelayer: remove unnecessary requirement on Rearmable

[michaeldgg2]

Minelayer requires Rearmable, but Minelayer does not use it. LayMines activity uses Rearmable, but it can work without it:

if ((minefield == null || minefield.Contains(self.Location)) && CanLayMine(self, self.Location))
{
    if (rearmableInfo != null && ammoPools.Any(p => p.Info.Name == minelayer.Info.AmmoPoolName && !p.HasAmmo))
    {
    // ...

This PR simply removes the mandatory dependency on Rearmable, making it possible to remove Rearmable trait on actors, which don't need to use it.

[PunkPun]

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