Adventure map, Tree of Knowledge, Right click info window, Display the cost of the tree of knowledge bonus when a recruited hero has already visited the tree of knowledge while under the command of another player

[LeHerosInconnu]

Preliminary checks

• I've checked that there aren't other open issues on the same topic.

Describe the problem requiring a solution

Display the cost of the tree of knowledge bonus in the right click info window when a recruited hero has already visited the tree of knowledge while under the command of another player.

From @zenseii:

If the tree of knowledge has already been visited by the hero, the cost to be paid should also be displayed.

The way I've come to see this mechanic of knowing what bonus objects a hero has visited and used, is that this is a gameplay feature. It answer the player's simple question of "Will there be any use for my hero to visit this location?"

As this PR is closed, I will open another issue for this.

Originally posted by @LeHerosInconnu in #9077 (comment)

I don't understand the choice of not displaying the cost to be paid in the right click information window.
If the hero has already benefited from the tree of knowledge bonus, the cost to be paid is known, so why not display it?

The player should be able to benefit from this information for his other heroes, this is not just for an individual hero.

What's the point of forcing the user to send another hero to find out the cost to be paid?
It just seems like an annoying micromanagement imposed on the player, who will even consider it a bug because it doesn't work in the same way as it does with his natively recruited heroes when they visit a tree of knowledge.

Describe the possible solution

If a hero, even one previously under another player's command, has benefited from the tree of knowledge bonus (or has simply visited the tree of knowledge), the cost of accessing the bonus should be indicated in the right click information window.

Additional info

Related PR: #9077.
Related discussion: #9081.