Additional block build over options (#7993)

* Adds missing block groups

* Allows electrolyzers to be rotated by bulding over them too

Co-authored-by: Garen7 <Garen7@users.noreply.github.com>

core/src/mindustry/world/blocks/distribution/DirectionalUnloader.java

@@ -28,6 +28,7 @@ public class DirectionalUnloader extends Block{
     public DirectionalUnloader(String name){
         super(name);
 
+        group = BlockGroup.transportation;
         update = true;
         solid = true;
         hasItems = true;

core/src/mindustry/world/blocks/payloads/PayloadConveyor.java

@@ -24,7 +24,7 @@ public class PayloadConveyor extends Block{
 
     public PayloadConveyor(String name){
         super(name);
-        group = BlockGroup.transportation;
+        group = BlockGroup.payloads;
         size = 3;
         rotate = true;
         update = true;