N21-2166 new fields to external tool form

[GordonNicholasCap]

Description

allow superhero to create/update external tools to be preferred tools with icon

Links to Tickets or other pull requests

• https://ticketsystem.dbildungscloud.de/browse/N21-2166
• https://github.com/hpi-schul-cloud/schulcloud-server/pull/5259
• https://github.com/hpi-schul-cloud/dof_app_deploy/pull/980
• https://github.com/hpi-schul-cloud/nuxt-client/pull/3412

Changes

Datasecurity

Deployment

New Repos, NPM pakages or vendor scripts

Screenshots of UI changes

Approval for review

• [x] All points were discussed with the ticket creator, support-team or product owner. The code upholds all quality guidelines from the PR-template.

Notice: Please remove the WIP label if the PR is ready to review, otherwise nobody will review it.