Fix #13513, ec492cb267: std::numeric_limits<CompanyMask> not working causes no vehicles to exist

std::numeric_limits<T>::max() returns 0 instead of an error when the type is unknown.
Solve it by implementing and using Set() and All() in BaseBitSet in same way as std::bitset.

src/saveload/engine_sl.cpp

@@ -109,7 +109,7 @@ struct ENGNChunkHandler : ChunkHandler {
 				 * Just cancel any previews. */
 				e->flags.Reset(EngineFlag{4}); // ENGINE_OFFER_WINDOW_OPEN
 				e->preview_company = INVALID_COMPANY;
-				e->preview_asked = std::numeric_limits<CompanyMask>::max();
+				e->preview_asked.Set();
 			}
 		}
 	}