Have port destination likelihood scale with level (#1473)

## Description:

Having a high level port would increase the number of outgoing
tradeships, but not the number of incoming tradeships. Now the the
chances of a tradeship landing on a port is scaled with the port's level

## 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 aggreement (only required once).

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

evan

src/core/game/PlayerImpl.ts

@@ -1165,23 +1165,19 @@ export class PlayerImpl implements Player {
         );
       });
 
-    // Make close ports twice more likely by putting them again
-    for (
-      let i = 0;
-      i < this.mg.config().proximityBonusPortsNb(ports.length);
-      i++
-    ) {
-      ports.push(ports[i]);
+    const weightedPorts: Unit[] = [];
+
+    for (const [i, otherPort] of ports.entries()) {
+      const expanded = new Array(otherPort.level()).fill(otherPort);
+      weightedPorts.push(...expanded);
+      if (i < this.mg.config().proximityBonusPortsNb(ports.length)) {
+        weightedPorts.push(...expanded);
+      }
+      if (port.owner().isFriendly(otherPort.owner())) {
+        weightedPorts.push(...expanded);
+      }
     }
 
-    // Make ally ports twice more likely by putting them again
-    this.mg
-      .players()
-      .filter((p) => p !== port.owner() && p.canTrade(port.owner()))
-      .filter((p) => p.isAlliedWith(port.owner()))
-      .flatMap((p) => p.units(UnitType.Port))
-      .forEach((p) => ports.push(p));
-
-    return ports;
+    return weightedPorts;
   }
 }