Upgrade TypeScript to ^6.0.3 (#56772)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/56772

Upgrades to TypeScript 6.0.3 and updates `typescript-eslint/*` for TS 6.0 compatibility across `react-native` and `metro`.

#### Motivation

TypeScript 6.0 (Mar 2026) will resolve https://github.com/facebook/react-native/issues/53565. Before updating in the React Native CLI template, align in RN and Metro source for consistency.

This is an internal change since:
- This upgrade only applies to TS analysis of these repos' source code.
- Edits to `react-native/typescript-config/tsconfig.json` (which *is* distributed) maintain backwards compatibility.

#### Changes

**react-native**

- Bump `typescript` from `^5.8.3` to `^6.0.3`
- Bump `typescript-eslint/*` from `^8.24.0` to `^8.59.2`
- Replace deprecated `moduleResolution: "node"` with `"node16"` and `target: "es5"` with `"es2015"` in codegen-typescript-test
- Add explicit `types: ["jest", "node"]` where needed (TS 6.0 defaults `types` to `[]`)
- Set `strict: false` in configs that only enable specific strict flags (TS 6.0 defaults `strict` to `true`)
- Update `ModuleResolutionKind.NodeJs` to `Node16` in build config

**metro**

- Bump `typescript` from `5.8.3` to `^6.0.3`
- Bump `typescript-eslint/*` from `^8.36.0` to `^8.59.2`
- No tsconfig changes needed (`tsconfig/node20` preset is already TS 6.0 compatible)

Changelog: [Internal]

Reviewed By: christophpurrer

Differential Revision: D104658690

fbshipit-source-id: 9a2feeb257d5783431941a911b17065fcd0389a5

scripts/js-api/build-types/templates/tsconfig.test.json

@@ -2,6 +2,7 @@
   "compilerOptions": {
     "module": "esnext",
     "lib": ["es2020"],
+    "strict": false,
     "noImplicitAny": true,
     "noImplicitThis": true,
     "types": [],