Provide a button on the context toolbar to edit the selected macro

With CKEditor, we have this behavior:

• there is a toolbar always visible, which has a button to insert or edit a macro call
• there is no context (balloon) toolbar shown when selecting a macro call
• if you click inside the output of a macro that is editable in-place you get a context toolbar with 2 buttons: one to edit the macro parameters and the other to insert a new macro; this is needed because both actions are possible in this context so the single button available on the top level toolbar is not enough (it wouldn't know what to do: edit the current macro or insert a new macro).
• you can double-click on the read-only part of a macro output to edit the macro parameters

With BlockNote, we currently have this behavior:

• there is no top level toolbar always visible (when the text selection is collapsed, i.e. you have only the caret)
• you can't select an inline macro call, XWIKI-24229
• when selecting a block-level macro call, we get a context toolbar that has a button to wrap the selected macro with a link (see XWIKI-24238)
• you can double-click on the read-only part of a macro output to edit the macro parameters

Without a top level toolbar (always visible) we need a way to advertise the macro edit feature. It makes sense to add the macro edit button on the context toolbar shown when selecting a macro.