Add translation for 'insert' in the sidebar

[piemonkey]

Overview

In the sidebar, this used to say 'Insert':

connected issues and PRs:

https://binnenland.atlassian.net/browse/GN-4665

Setup

Recommended, some way to change locales easily, e.g. this extension

How to test/reproduce

Open any agendapoint or regulatory statement and confirm that the word 'insert' is in the correct language (NL for anything but locale of en-US).

Challenges/uncertainties

I don't know the correct dutch and there seems to be difference with the insert-label translation.

Checks PR readiness

• UI: works on smaller screen sizes
• UI: feedback for any loading/error states
• Check cancel/go-back flows
• Check database state correct when deleting/updating (especially regarding relationships)
• changelog
• npm lint
• no new deprecations