feat: implement file remove listener for upload (24.4)

[ugur-vaadin]

Description

Based on the suggested API, this PR:

• Introduces addFileRemoveListener for Upload
• Introduces FileRemovedEvent
• Fixes the testClearFileList test which was a false positive
• Adds a test for the new API
• Makes the TestBench API removeFile public

!!! IMPORTANT !!! - Should be merged to the new minor branch.

Fixes #1342

Type of change

• Bugfix
• Feature

Checklist

• I have read the contribution guide: https://vaadin.com/docs/latest/contributing/overview
• I have added a description following the guideline.
• The issue is created in the corresponding repository and I have referenced it.
• I have added tests to ensure my change is effective and works as intended.
• New and existing tests are passing locally with my change.
• I have performed self-review and corrected misspellings.
• Enhancement / new feature was discussed in a corresponding GitHub issue and Acceptance Criteria were created.

[sonarcloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

3 New issues
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[vaadin-bot]

This ticket/PR has been released with Vaadin 24.4.0.alpha1 and is also targeting the upcoming stable 24.4.0 version.