[11.x] Fix Middleware::trustHosts(subdomains: true)

[axlon]

Fixes #50845

This PR fixes 2 problems with Middleware::trustHosts():

8e0eb64:

When Middleware::trustHosts() is called with hosts (e.g. $middleware->trustHosts(['127.0.0.1'])) it immediately tries to configure the TrustHosts middleware. The TrustHosts middleware itself is reliant on the application's config, so it cannot be configured this early in the bootstrapping process. This is fixed by only setting what we need to do, but not doing it until a request happens.

a6171fd:

Its not uncommon to rely on certain container services when deciding on what hosts to trust, but because the Middleware::trustHosts() method only accepts an already resolved array and happens so early in the bootstrapping process we cannot use those services yet.

This is fixed by allowing developers to pass a callback that "lazily" resolves the hosts. This enables the following:

$middleware->trustHosts(fn () => config('app.allowed_hosts'));