refactor: remove vuex store in external app

[JammingBen]

Description

Removes the vuex store module in the external app.

Also refactors the external app handling in general so that external mime types are now registered as ApplicationFileExtension. This allows us to:

• handle file actions for internal and external apps the same (mostly), which results in a lot less boilerplate code.
• keep the external app logic inside the corresponding package while not leaking into other apps like before.

Related Issue

• refs Migrate from vuex store to pinia #10210
• fixes Resolve business logic leaks ofweb-app-external #10256

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests
• Documentation
• Maintenance (e.g. dependency updates or tooling)

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[dschmidt]

I'm biased, but I love it :)

[sonarcloud]

Quality Gate failed

Failed conditions

13.33% Condition Coverage on New Code (required ≥ 50%)

See analysis details on SonarCloud