Simple modifications were made

[team10-h]

Fixes #6601
Fixes #7729
Some minor modifications were made to #7729, because the original code contained some errors. We simply fixed some known errors.

• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked documentation: Is the information available and up to date? If not created an issue at https://github.com/JabRef/user-documentation/issues or, even better, submitted a pull request to the documentation repository.

Our team worked on the issue #7729, and we tried to get a right click menu for main table header. In our revision, we can add or remove the columns to the main table in the preferences dialog in the right click menu.This is the table containing the columns in main table header. We can remove one column by clicking the button next to it. And we can also add a column by inputing anyone in the line and click the plus button next to it. Then when we save the changes, we can see main table has been changes. And we can also make the existing column visible or invisible by clicking on the item of right click menu.Because of time, we couldn't make better changes.

[calixtus]

There is something seriously wrong with your branch. Can you make sure you merged the latest main branch into yours?

[calixtus]

Since we have no reaction from anyone, who created this PR and the PR is in it's current state not reviewable, I'm closing this one. Please try to set up your workspace according to our guide next time and use a current base branch for your PRs.