refactor: improve serverlist validation script

The commit refactors the serverlist validation script to include a new check. It now compares all game servers listed in `serverlist.csv` to `$shortname-icon.png` files in `lgsm/data/gameicons`. If a game server is listed in `serverlist.csv`, it should have a corresponding `$shortname-icon.png` file. The commit adds a loop that checks for the existence of these files and outputs an error message if any are missing.

.github/workflows/serverlist-validate.sh

@@ -19,4 +19,19 @@ for csv in $csvlist; do
 	fi
 done
 
+# Compare all game servers listed in serverlist.csv to $shortname-icon.png files in lgsm/data/gameicons
+# if the game server is listed in serverlist.csv then it will have a $shortname-icon.png file
+
+# loop though shortname in serverlist.csv
+echo "Checking that all the game servers listed in serverlist.csv have a shortname-icon.png file"
+for shortname in $(tail -n +2 serverlist.csv | cut -d ',' -f1); do
+	# check if $shortname-icon.png exists
+	if [ ! -f "gameicons/${shortname}-icon.png" ]; then
+		echo "ERROR: gameicons/${shortname}-icon.png does not exist"
+		exitcode=1
+	else
+		echo "OK: gameicons/${shortname}-icon.png exists"
+	fi
+done
+
 exit ${exitcode}