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/view/PlayerView.ts

@@ -29,6 +29,7 @@ import {
 } from "../../core/game/GameUpdates";
 import { UserSettings } from "../../core/game/UserSettings";
 import { PlayerState, PlayerStatic, PlayerTypeEnum } from "../render/types";
+import { themeProvider } from "../theme/ThemeProvider";
 import { GameView } from "./GameView";
 import { UnitView } from "./UnitView";
 
@@ -133,7 +134,7 @@ export class PlayerView {
       this.anonymousName = createRandomName(data.name!, data.playerType!);
     }
 
-    const theme = this.game.config().theme();
+    const theme = themeProvider.current();
 
     const defaultTerritoryColor = theme.territoryColor(this);
     const defaultBorderColor = theme.borderColor(defaultTerritoryColor);