Add RequiresSpecificOwners trait

To enforce specific owners via Lint rules,
and possibly other means later.
This is for cases where accidentally setting an
unfitting owner via editor could cause issues.

Example: AI might try to attack Creeps-owned trees
and get stuck.

OpenRA.Mods.Common/OpenRA.Mods.Common.csproj

@@ -501,6 +501,7 @@
     <Compile Include="Traits\RepairsBridges.cs" />
     <Compile Include="Traits\Replaceable.cs" />
     <Compile Include="Traits\Replacement.cs" />
+    <Compile Include="Traits\RequiresSpecificOwners.cs" />
     <Compile Include="Traits\SeedsResource.cs" />
     <Compile Include="Traits\StoresResources.cs" />
     <Compile Include="Traits\Render\SelectionDecorations.cs" />