lumino: update the dragdrop and widgets pakcages to the latest

[safisa]

What it does

Should fix the splitter dragging between a custom editor (or a webview) and another editor.

How to test

Follow-ups

Breaking changes

• This PR introduces breaking changes and requires careful review. If yes, the breaking changes section in the changelog has been updated.

Attribution

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines
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Reminder for reviewers

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[ndoschek]

Thank you for the PR!
Just FYI: we currently maintain a patch for @lumino/widgets at dev-packages/cli/patches/@lumino+widgets+2.7.2.patch (see #15680 for background). Since this PR bumps @lumino/widgets from 2.7.2 to 2.7.5, the existing patch will no longer apply. I'm happy to update the patch to the new version, verify locally that it works as expected, and then get back to you.

We do plan to upstream these changes to Lumino at some point, I'll keep track of that.

[safisa]

Hi @ndoschek
Do you mean you need to revert the changes made in this PR: #15643, because they may no longer be relevant?