Tree-like objective node structure (#7152)

* overall structure

* overall layout

* field interpreter

* less bloated UI

* scroll pan't

* strip off the 'Marker' suffix

* e

* all (hopefully all...) interpreters finished.

* onset

* two, four

* i don't understand how icon mappings work.

* separate remover and indexer

* some cleanups

* untested mobile support

* contrib

* ok anuke

* fix conflicts 2

* hidden

core/src/mindustry/editor/MapInfoDialog.java

@@ -77,7 +77,7 @@ public class MapInfoDialog extends BaseDialog{
                 r.row();
 
                 r.button("@editor.objectives", Icon.info, style, () -> {
-                    objectives.show(state.rules.objectives);
+                    objectives.show(state.rules.objectives.all, state.rules.objectives.all::set);
                     hide();
                 }).marginLeft(10f);