UIEXT-3150: Expose @SaveAdditional

UIEXT-3150 (WebUI-Migration Excel Reader)

Author: PaulBrnrther

org.knime.core.ui/META-INF/MANIFEST.MF

@@ -33,6 +33,7 @@ Export-Package: org.knime.core.ui;x-internal:=true,
  org.knime.core.webui.node.dialog.defaultdialog.dataservice.impl;x-friends:="org.knime.python3.nodes",
  org.knime.core.webui.node.dialog.defaultdialog.history;x-internal:=true,
  org.knime.core.webui.node.dialog.defaultdialog.internal;x-internal:=true,
+ org.knime.core.webui.node.dialog.defaultdialog.internal.additionalsave;x-internal:=true,
  org.knime.core.webui.node.dialog.defaultdialog.internal.button;x-internal:=true,
  org.knime.core.webui.node.dialog.defaultdialog.internal.dynamic;x-internal:=true,
  org.knime.core.webui.node.dialog.defaultdialog.internal.dynamic.extensions.createcell;x-internal:=true,