add x button for closing a panel

[Simsalabim1234]

User-Facing Changes

Description
This PR removes the "Remove Panel" button from the dropdown list when clicking the settings button of a panel, and instead adds an x button right next to it. This shall make closing a panel easier.

Checklist

• The web version was tested and it is running ok
• The desktop version was tested and it is running ok
• I've updated/created the storybook file(s)
• The release version was updated on package.json files

[turtle-operator]

Fine for me, works as expected locally.

[aneuwald-ctw]

@Simsalabim1234 could you check the errors regards to the CI Pipeline? It seems that there is some unused variables.

You can try to fix locally and run the command "lint:ci", which will give you the errors before going to CI again :)

[markushankh-bmw]

There is a tradeoff between conveniently closing the panel and accidentally closing it when in fact you wanted to hit one of the other buttons. I would argue that closing the panel of a layout is not a task you have to do very frequently, so I'd rather avoid the accidental closing as it can be cumbersome to reopen a panel, reconfigure it and place it in the right spot. However, an option could be to offer this as a setting for users who might often have the panel-closing step in their workflow.

[aneuwald-ctw]

This PR will not be accepted at this time, because it is not a priority on the project. It can be a good improvement, but it can also impact the UX, as users can close panels by accident. If in the future it become a high priority request, we can reopen this Pull Request.

[Simsalabim1234]

@aneuwald-ctw @markushankh-bmw Yes I understand that having this x-button might be dangerous :) Maybe we can add it in the future as an option, but it's also fine to leave it like it is. Thanks for your feedback!