Tiptap integration #2426

Initial Checklist

• I understand this is a user story and questions should be posted in the Community Discussions
• I searched issues and couldn’t find anything (or linked relevant results below)

User Story

• As a developer, I want to use a generic editor component so that I don't need to take care of text editing and content conversion myself.

User Value

Great UX and DX for editing content / offering content editing and rendering

Acceptance Criteria

• our own editor component utilizing tiptap is available for every developer to use (see https://github.com/opencloud-eu/internal/issues/238#issuecomment-3853946230 for details if you have access 🤪 )
• decision as part of the outcome: publish as new package or as part of web-pkg?
• tiptap-integration in web-app-mail gets replaced by new editor component
• markdown editor integration in web-app-text-editor gets replaced by new editor component
• TextEditor component in web-pkg gets replaced by new editor component, so that the new one is being used for any markdown rendering as well
• editor features of the first iteration (more to come later):
  • text editing area
  • optional, context sensitive toolbar
  • optional, context sensitive slash commands menu
  • content support for at least plain text, markdown, html and tiptap-json