Fix src/user tests

[digitalbase]

Went down a rabbit hole in NDK 3.x with a bug around fetching user profile data (and zap methods). See #363

To reproduce i decided to improve the user tests and create a case that failed/showed the problem.

This PR has:

• EventGenerator refactor: Replace any with NDK
• EventGenerator refactor: Some helper methods, better types for pubkey
• NDK User tests: Make time deterministic (using Vitest fake timers https://vitest.dev/config/faketimers)
• NDK User tests: Don't use deprecated fields/methods like getUser and image field
• NDK User tests: Truely test race criteria for old/new profile updates
• NDK User tests: Add a test to prove Retrieving getZapMethods twice returns empty map (ndk 3.0-beta) #363

The last item i think proves the bug

it("duplicate fetching of profile", async () => {
            const event = EventGenerator.createEvent(
                0,
                JSON.stringify({
                    name: "Jeff",
                    picture: "https://image.url",
                }),
                pubkey,
            );
            event.created_at = NOW_SEC - 7200;

            ndk.fetchEvent = vi.fn().mockResolvedValueOnce(event);

            const profile = await user.fetchProfile();
            expect(profile?.name).toEqual("Jeff");
            expect(profile?.picture).toEqual("https://image.url");

            const profile2 = await user.fetchProfile();
            expect(profile2?.name).toEqual("Jeff");
            expect(profile2?.picture).toEqual("https://image.url");
        });