Added localization build

[sunghyunkang1111]

What this PR does

Introduces internationalization (i18n) support using react-i18next, applied to the SplashScreen as a proof-of-concept.

Option 1: String literal keys (no build step)

import { t } from "Localization/t";
t("splashScreen.title.default");

Pros

1. No build step — t() infers valid keys from Resources.json via the ResourceKey type at compile time
2. Simpler setup, fewer moving parts

Cons

1. Raw strings — no autocomplete beyond what TS string unions provide
2. No hover preview of English values
3. Renaming a key in JSON requires find-and-replace across call sites

Option 2: Generated Keys const object

import { Keys } from "Localization/Keys.generated";
import { t } from "Localization/t";
t(Keys.splashScreen.title.default);

Pros

1. Full autocomplete — Keys triggers IntelliSense through the whole key tree
2. Hover shows English text — JSDoc on every leaf: /** Welcome to Azure Cosmos DB */

3. Rename-safe — changing a key in JSON + regenerating updates the const; TS errors surface all broken call sites

Cons

1. Requires a generate step
2. If not committing the generated file, initial compilation issue will surface while developing
3. Need to wire regenerating the string types when hot-loading
4. Need to maintain the generation script which uses few 3rd party libraries and some custom logic as well