Revert "Replace iterator with forEach"

This reverts commit f4ace05.

Author: sunkup

lib/src/main/java/at/bitfire/cert4android/UserDecisionRegistry.kt

@@ -94,8 +94,11 @@ class UserDecisionRegistry private constructor(
 
         // continue work that's waiting for decisions
         synchronized(pendingDecisions) {
-            pendingDecisions[cert]?.forEach { cont ->
-                cont.resume(trusted)
+            pendingDecisions[cert]?.iterator()?.let { iter ->
+                while (iter.hasNext()) {
+                    iter.next().resume(trusted)
+                    iter.remove()
+                }
             }
 
             // remove certificate from pendingDecisions so UI can be shown again in future