Consider removing the duplicate "copy link" and "open link" buttons

Description of the new feature

If a message begins with a link, right clicking the link shows two redundant options: Copy Link Location and Copy Link Address.

If the link is in the middle of a message, there's only one option: Copy Link Address

Thus it is more useful than the other one, as it works in more cases.

Copy Link Address comes from GTK. But previously, it didn't work on all systems. That's why the Gajim maintainers had to add the Copy Link Location option.

But now that Gajim switched to GTK4, it should be confirmed whether Copy Link Address still has portability issues. If that's not the case, then Copy Link Location can be dropped.

Edit: The same probably applies for the Open Link buttons