Set territory pattern on purchase (#1932)

## Description:

When purchasing a territory pattern, set it after successful purchase

## 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

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

evan

src/client/TerritoryPatternsModal.ts

@@ -97,7 +97,7 @@ export class TerritoryPatternsModal extends LitElement {
         <pattern-button
           .pattern=${pattern}
           .onSelect=${(p: Pattern | null) => this.selectPattern(p)}
-          .onPurchase=${(priceId: string) => handlePurchase(priceId)}
+          .onPurchase=${(p: Pattern) => handlePurchase(p)}
         ></pattern-button>
       `);
     }