Composer: add undo button to text formatting

### Your use case

#### What would you like to do?

Undo atctions when i format text with the text formatter

#### Why would you like to do it?

You often select sections and do operations on already written text. There is the danger of loosing work even if the formatter is bug-free and well designed. There is a high chance of user error or missinterpreting functionality.

#### How would you like to achieve it?

Best would be to add Undo and Redo buttons to the text-formatting view of the composer. Ideally, they should not clutter the formatting options list any further but be more discoverable — maybe placed in the top-left corner next to the expansion handle.

### Have you considered any alternatives?

No idea

### Additional context

Maybe related to: #2796

### Are you willing to provide a PR?

No

Start by inspecting the Composer text-formatting view and the related issue #2796. Determine how formatting changes are applied and where undo and redo controls could be placed near the expansion handle without cluttering the options. Done means users can undo and redo formatting operations without losing existing text.

Written by the indexing model from the issue text.