New hooks POC

[tusharpandey13]

Hooks for auth handlers
GH issue: #1895
A POC is present here: https://github.com/auth0/nextjs-auth0/tree/poc/new-hooks

The following hooks are added to client.ts (and hence, to auth-client.ts):

    beforeLogin?: BeforeLoginHook;
    afterLogin?: AfterLoginHook;
    beforeLogout?: BeforeLogoutHook;
    afterLogout?: AfterLogoutHook;
    beforeCallback?: BeforeCallbackHook;

and can be defined on initalization.

Type definitions and hooks implementation is present in auth-hooks.ts and all hooks return a Promise<NextResponse | void> to factor for both redirection / mutation operations.