feat: add Rollup configuration for ESM build

- Created rollup.config.js to bundle the ESM version of the library.
- Set up TypeScript plugin with appropriate options for source maps and comment removal.

fix: ensure non-null assertions in Memoized class

- Updated tryGet and iterator methods to use non-null assertions for cached values.

test: add comprehensive tests for Memoized functionality

- Implemented tests to verify caching behavior, iterator functionality, and random access in Memoized class.

chore: update TypeScript configuration files

- Modified tsconfig.cjs.json and tsconfig.esm.json to enable emitting output and source maps.
- Refined tsconfig.json to improve strictness and remove unnecessary options.
- Updated tsconfig.types.json to specify output directory for type declarations.
- Removed tsconfig.umd.json as it is no longer needed.

Author: electricessence

.build/validate-package.js

@@ -0,0 +1,16 @@
+/*!
+ * @author electricessence / https://github.com/electricessence/
+ * Licensing: MIT
+ */
+export declare class Memoized<T> implements Iterable<T>, Iterator<T> {
+    private _iterator;
+    private readonly _cached;
+    constructor(source: Iterable<T>);
+    hasCached(index: number): boolean;
+    ensure(index: number): boolean;
+    get(index: number): T | undefined;
+    tryGet(index: number, out: (e: T) => void): boolean;
+    [Symbol.iterator](): Iterator<T>;
+    next(): IteratorResult<T>;
+}
+export default function memoize<T>(source: Iterable<T>): Memoized<T>;