Addition of FlagInputModal (#1606)

## Description:

The UI for selecting flags differs from other existing UIs, so this
change allows it to use .
The actual contents for flag selection will be included in the next PR.

## 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:

aotumuri

---------

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

src/client/Main.ts

@@ -11,6 +11,7 @@ import "./DarkModeButton";
 import { DarkModeButton } from "./DarkModeButton";
 import "./FlagInput";
 import { FlagInput } from "./FlagInput";
+import { FlagInputModal } from "./FlagInputModal";
 import { GameStartingModal } from "./GameStartingModal";
 import "./GoogleAdElement";
 import { HelpModal } from "./HelpModal";
@@ -194,6 +195,16 @@ class Client {
       hlpModal.open();
     });
 
+    const flagInputModal = document.querySelector(
+      "flag-input-modal",
+    ) as FlagInputModal;
+    flagInputModal instanceof FlagInputModal;
+    const flgInput = document.getElementById("flag-input_");
+    if (flgInput === null) throw new Error("Missing flag-input_");
+    flgInput.addEventListener("click", () => {
+      flagInputModal.open();
+    });
+
     const territoryModal = document.querySelector(
       "territory-patterns-modal",
     ) as TerritoryPatternsModal;