Move to TypeScript (#3830)

This moves our JS file to use TS instead, which allows us to use a proper linter to check the code.
All related files where moved out from the root in a dedicated folder to avoid polluting the Rust environment.

src/platform_impl/web/script/tsconfig.json

@@ -0,0 +1,14 @@
+{
+	"compilerOptions": {
+		"target": "ESNext",
+		"allowUnreachableCode": false,
+		"allowUnusedLabels": false,
+		"exactOptionalPropertyTypes": true,
+		"noImplicitOverride": true,
+		"noPropertyAccessFromIndexSignature": true,
+		"noUncheckedIndexedAccess": true,
+		"noUnusedLocals": true,
+		"noUnusedParameters": true,
+		"strict": true,
+	}
+}