feat(tabBar): Configurable TabBar actions (disable/hide close & disable/hide openDocument)

[lstraka-telekom]

Description

While the library already supports disabling certain commands in the main toolbar, the **TabBar currently lacks any configuration. I do not like to implement own tab for handling multiple initial documents, as the default almost cover everything for our use-cases.

The TabBar includes built-in action elements such as:

• Closing the active document (tab close)
• Opening a new document (new tab / openDocument)

At the moment, these actions are always available when the TabBar is visible, and there is no official way to disable or hide them via configuration.

Problem

In some use cases, the TabBar is needed for document navigation, but its default actions are too permissive:

• It is not possible to prevent users from closing the currently active document
• It is not possible to disable or hide the "open new tab" action (openDocument)