Update workflow editor to v2.1.0 (translated UI, refreshed look, remove redundant descriptions)

[Erikmitk]

Summary

This PR updates the embedded workflow editor (bpmn-js customization) to version 2.1.0 and resolves two long-standing UX issues with the editor's UI strings and property panel.

The editor source and full changelog are available at: https://github.com/Erikmitk/kitodo-workflow-editor/releases/tag/v2.1.0

Changes

Translation of palette and context pad tooltips (closes #3654)

Palette tooltips (e.g. "Append Gateway", "Create Start Event") and context pad action labels are now translated into German and English. Language is detected from document.body.lang rather than a hidden input, making detection reliable regardless of JSF render order. Spanish (es) support is also included.

Removal of redundant property descriptions (closes #4786)

The "Documentation" group, which contained redundant and inconsistently applied descriptions for only two task properties ("Metadata" and "Automatic"), has been removed from the properties panel entirely.

Additional fixes

• Properties panel header type label now updates correctly when switching between elements (MutationObserver + textNode.nodeValue patching to preserve React's internal Text node references)
• General group label in the properties panel is now translated
• getLocalizedStringForKey hardened against timing edge cases during initialisation

Files changed

• Kitodo/src/main/webapp/WEB-INF/resources/js/modeler_custom.js — language detection and localisation helper
• Kitodo/src/main/webapp/WEB-INF/resources/js/modeler_min.js — updated minified editor bundle (v2.1.0)
• Kitodo/src/main/webapp/WEB-INF/resources/css/modeler.css — updated editor stylesheet
• Kitodo/src/main/webapp/WEB-INF/resources/font/ — BPMN icon font files (new)

[Erikmitk]

@solth Once we get this approved and merged I'd like to mark this as the point of transferring the editor repo into the Kitodo organization. It lives in my personal space but it is an integral part of Kitodo.Production. So it seems wrong that the code is detached from the org. I can still keep it up-to-date but probably need the appropriate permissions after the move.