Add auto-upgrade buildings feature with middle mouse click (#1597)

## Description:

This PR implements a new feature allowing automatic upgrade of the
nearest building using the middle mouse button. This feature greatly
simplifies the upgrade process that previously required a right-click +
building recreation.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I have read and accepted the CLA agreement (only required once).

## Please put your Discord username so you can be contacted if a bug or
regression is found:

Kipstzz

---------

Co-authored-by: Scott Anderson <662325+scottanderson@users.noreply.github.com>

resources/lang/en.json

@@ -43,6 +43,7 @@
     "action_move_camera": "Move camera",
     "action_ratio_change": "Decrease/Increase attack ratio",
     "action_reset_gfx": "Reset graphics",
+    "action_auto_upgrade": "Auto-upgrade nearest building",
     "ui_section": "Game UI",
     "ui_leaderboard": "Leaderboard",
     "ui_your_team": "Your team:",