fix(types): specify ArrayBuffer as a backing buffer type for Response.body and Response.bytes

[magurotuna]

This patch updates the Response interface type declarations to correctly specify ArrayBuffer as the backing buffer type for the encode() method, aligning with the spec and addressing the change introduced in TypeScript 5.7 about making ArrayVBufferLike a default buffer type behind Uint8Array.

In fact, TypeScript's dom.d.ts got a similar change, and now it looks like:

interface Body {
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/Request/body) */
    readonly body: ReadableStream<Uint8Array<ArrayBuffer>> | null;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/Request/bodyUsed) */
    readonly bodyUsed: boolean;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/Request/arrayBuffer) */
    arrayBuffer(): Promise<ArrayBuffer>;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/Request/blob) */
    blob(): Promise<Blob>;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/Request/bytes) */
    bytes(): Promise<Uint8Array<ArrayBuffer>>;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/Request/formData) */
    formData(): Promise<FormData>;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/Request/json) */
    json(): Promise<any>;
    /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/Request/text) */
    text(): Promise<string>;
}

Refs

• Support generic Uint8Array<ArrayBuffer> microsoft/TypeScript-DOM-lib-generator#1944
• fix(types): specify ArrayBuffer as a backing buffer type for TextEncoder.encode() #30434

[dsherret]

Similarly to #30434 (comment) -- I think we should wait for TypeScript 5.9 before landing this change.

[dsherret]

LGTM now too