New menu entries for creating sub-objects on community and collection pages

[EikLoe]

References

Add references/links to any related issues or PRs. These may include:

• Fixes New "Add sub-objects entry" in edit-menus on community or collection pages #5825 and Collection submit button #2556

Description

This PR adds new entries to the dso-edit menus on community and collection pages. Those entries allow you to directly add sub-objects such as communities or collections to an existing community or submit a new item in a collection.
In addition a new Submit item button will be added to the collection page, if collection.showSubmitButton is set to true.
If you're a logged in as a submitter and your frontend is configured to show the submit button the collection page should look like this:

If collection.showSubmitButton is set to false, the Submit item functionality is hidden in the dso-edit menu of the collection page:

Instructions for Reviewers

Please add a more detailed description of the changes made by your PR. At a minimum, providing a bulleted list of changes in your PR is helpful to reviewers.

List of changes in this PR:

• Added new AddSubObjectsMenuProvider in order to allow directly adding subcollections or subcommunities to an existing community
• Added new SubmitNewItemMenuProvider to allow directly submitting items via the dso-edit menu on collection pages.
• Created a new configuration entry for showing a submit button on collection pages
• Added the new submit button on collection pages
• Created and updated spec and e2e tests.

Include guidance for how to test or review your PR. This may include: steps to reproduce a bug, screenshots or description of a new feature, or reasons behind specific changes.

1. Login as a community administrator and navigate to the community where you have admin privileges to.
2. Make sure, you see the new Add community and Add collection entries in the dso-edit menu and test their functionality
3. Navigate to a collection where you have at least submitter privileges: make sure you can see the new Add item entry in the dso-edit menu.
4. Add the following configuration to your config.yml and rebuild your frontend:

collection:
  showSubmitButton: true

5. Navigate to a collection where you have at least submitter privileges: make sure, the new Submit item button appears on the collection page. The menu entry should not be visible any more.

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[EikLoe]

I'm still not sure, whether we want the Submit button to display the text "Submit Publication" or "Submit JournalIssue" on collections with the specific entity types.