Feature/Move theme system from core to client-side ThemeProvider (#4108)

**Add approved & assigned issue number here:** 

Resolves #2549

## Description:

Themes are purely for the client's rendering, and the server doesn't
need context on them. This PR moves `Theme.ts` from
`src/core/configuration` to `src/client/theme` and moves affiliation
colors to `render-settings.json`.

This is to support the ability to add additional themes more quickly,
such as colorblind-friendly themes. No visible changes occur from this
refactor.

## 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

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

jetaviz

---------

Co-authored-by: Josh Harris <josh@wickedsick.com>

src/client/ClientGameRunner.ts

@@ -75,6 +75,7 @@ import {
 } from "./render/gl";
 import { ALL_UNIT_TYPES, UnitState } from "./render/types";
 import { SoundManager } from "./sound/SoundManager";
+import { themeProvider } from "./theme/ThemeProvider";
 
 export interface LobbyConfig {
   cosmetics: PlayerCosmeticRefs;
@@ -110,6 +111,7 @@ export function joinLobby(
   console.log(`joining lobby: gameID: ${lobbyConfig.gameID}`);
 
   const userSettings: UserSettings = new UserSettings();
+  themeProvider.reset(); // fresh colour allocators for this game
   startGame(lobbyConfig.gameID, lobbyConfig.gameStartInfo?.config ?? {});
 
   const transport = new Transport(lobbyConfig, eventBus);