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/core/configuration/Config.ts

@@ -21,9 +21,6 @@ import { UserSettings } from "../game/UserSettings";
 import { GameConfig, TeamCountConfig } from "../Schemas";
 import { NukeType } from "../StatsSchemas";
 import { assertNever, sigmoid, toInt, within } from "../Util";
-import { PastelTheme } from "./PastelTheme";
-import { PastelThemeDark } from "./PastelThemeDark";
-import { Theme } from "./Theme";
 
 declare global {
   interface Window {
@@ -84,8 +81,6 @@ export const JwksSchema = z.object({
 export const SAM_CONSTRUCTION_TICKS = 30 * 10;
 
 export class Config {
-  private pastelTheme: PastelTheme = new PastelTheme();
-  private pastelThemeDark: PastelThemeDark = new PastelThemeDark();
   private unitInfoCache = new Map<UnitType, UnitInfo>();
   constructor(
     private _gameConfig: GameConfig,
@@ -562,11 +557,6 @@ export class Config {
   numBots(): number {
     return this.bots();
   }
-  theme(): Theme {
-    return this.userSettings()?.darkMode()
-      ? this.pastelThemeDark
-      : this.pastelTheme;
-  }
 
   attackLogic(
     gm: Game,