Restore the old behavior for the "Open a new tab" button

In MR !50 (merged) (New tabs start in the current folder and can be inserted next to the current tab or at the end) was introduced the new behavior for the "Open a new tab" button.
The motivational part of the changes made is as follows:

People who use Konsole, Double Commander, Total Commander or Dolphin are used to the fact that when they open a new tab, it starts from the same folder that they were using. When trying Krusader, they do not expect that new tabs start from the home folder. After applying the present changes, new tabs start in the current folder, like it happens with the other programs.

In this regard, I have a question: what about people who are accustomed to the old "classical" behavior of the "Open a new tab" button, and the new behavior does not suit them? (I belong to such people).
A compromise can be reached by preserving both approaches. This MR does it. The option "Old behavior for new tab button" has been added to the program settings.

P.S.
As Nikita (@melnichenko) noted in this topic (#447394), a terminological discrepancy occur between the new behaviors and points of the context menu.

Besides this, popup menu looks wrong now - there are two options "New Tab" and "Duplicate Current Tab", which do the same thing (shortcut actions have the same issue). Users will definitely consider this a bug. Moreover, the icon for the "New Tab" in popup is the same as on the New Tab button in the tab toolbar, which gives the idea that it should open a fresh tab.

I propose to dynamically change the context menu depending on the selected model of behavior. This is a question for discussion.