Submit to Community Library panel

[Jakoma02]

Summary

This PR implements a side panel for submitting channels to the Community Library.

I manually tested the changes by interacting with it in the browser, tried network throttling simulation to check the experience for users on slow networks, and tried switching the interface to Arabic to see how it handles RTL languages.

Detailed changes

• Implemented the SubmitToCommunityLibrarySidePanel component
• Added a "Share" dropdown in TreeViewBase
• Added addPublishedData method to the existing Channel resource
• Added a new CommunityLibrarySubmission resource
• Added constants for Community Library submission statuses
• Added shared string for Community Library submission statuses
• Moved a configured i18n-iso-countries instance to a separate util file to allow reuse outside CountryField
• Added a fullWidth prop to CountryField to allow stretching the whole parent container width
• Moved metadata strings from a mixins file to a separate shared strings file
• Moved metadata translation logic from a mixin to a standalone translateMetadataString util function (motivated by making it easier to use this logic from components using the composition API, where using mixins is not practical)

References

Resolves #5262.

Reviewer guidance

The UX of the panel when it is loading data it needs to display was invented by me and needs to be especially checked from a design perspective. Also, warnings for when the channel is already public or when the latest published version of the channel already has a submission to the community library were not present in the initial design and should be especially checked.

Unresolved questions

• The KTextbox component from KDS does not display correctly when an RTL language is used

• The categories cannot be changed in the submission form, but are allowed to be changed on the backend; the backend implementation should be changed so that this is not supported