Remove Bitstreams on edit-item-page doesn't work

[alexandrevryghem]

References

• Fixes Remove Bitstreams on edit-item-page doesn't work  #3116
• Related Fixed creation & deletion of relationships not working correctly & added same entity type relationship support #3060
• Port [Port main] Remove Bitstreams on edit-item-page doesn't work #3127

Description

Fixed the issue on the edit bitstream tab from the item page, and also fixed the same kind of performance issues on the Content Source tab from edit collection.

Instructions for Reviewers

List of changes in this PR:

• Fixed the issue on the edit bitstream tab. This issue has been fixed by replacing the observableZip with an observableCombineLatest because when you have multiple bundles, the this.objectUpdatesService.hasUpdates won't emit for all the bundles causing the observableZip not to emit and update it's value. By changing it to an observableCombineLatest even when one bundle has been changed the whole observable will update.
• The same type of optimisation (like done on the edit relationship & edit bitstream tab) also still needed to be applied to the Content Source tab from edit collection so I also fixed this at the same time

Checklist

• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes ESLint validation using yarn lint
• My PR doesn't introduce circular dependencies (verified via yarn check-circ-deps)
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• If my PR fixes an issue ticket, I've linked them together.

[alexandrevryghem]

While testing this PR I discovered that the discard & save buttons were not automatically disabled again after deleting a bitstream. I tested this on the dspace-7.6 tag and was also able to reproduce it there. This is caused by a bigger caching issue, so I'm putting this PR as "Ready for review" and will try to contribute a fix for that issue too but this will most likely be for 8.1

[EikLoe]

Thanks @alexandrevryghem for the fix!
I tested it locally and it worked fine for me.

[tdonohue]

Closing & reopening to reboot GitHub actions. (For some reason they didn't spin up properly with this PR.)

[tdonohue]

@alexandrevryghem : Is there also a main version of this PR? I believe this bug is occurring on both 7.x and main. (I tried pulling this PR into main but there's several conflicts)

[alexandrevryghem]

@tdonohue: I created the port PR #3127

[tdonohue]

👍 Thanks again @alexandrevryghem ! Tested this via #3127.. Verified this code is identical for 7.x.