freenet: repair WebOfTrust plugin

Before, we received:

```
The plugin WebOfTrust could not be loaded: class java.lang.reflect.InaccessibleObjectException: Unable to make field private final java.lang.String java.lang.Enum.name accessible: module java.base does not "opens java.lang" to unnamed module @365185bd
at java.base/java.lang.reflect.AccessibleObject.throwInaccessibleObjectException(AccessibleObject.java:391)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:367)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:315)
at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:183)
at java.base/java.lang.reflect.Field.setAccessible(Field.java:177)
at com.db4o.internal.JDK_1_2.setAccessible(JDK_1_2.java:150)
at com.db4o.internal.Platform4.setAccessible(Platform4.java:615)
```

More info: https://stackoverflow.com/a/74714838

pkgs/by-name/fr/freenet/freenetWrapper

···
 chmod u+rw -- $FREENET_HOME/seednodes.fref
 
 cd -- $FREENET_HOME
-exec @jre@/bin/java -Xmx1024M freenet.node.NodeStarter "$@"
+# The `--add-opens` lines are needed to get the WebOfTrust plugin to work.
+exec @jre@/bin/java -Xmx1024M \
+  --add-opens java.base/java.lang=ALL-UNNAMED \
+  --add-opens java.base/java.nio=ALL-UNNAMED \
+  --add-opens java.base/sun.nio.ch=ALL-UNNAMED \
+  freenet.node.NodeStarter "$@"