Let a client account expire on a date

Staff can give a client an expiry date on the create and edit screens,
and through /api/v1/clients. When the date passes, the client is refused
at sign-in and on their next request, and their API access ends too.
Files and history stay, and a later date (or none) brings them back.

Access is checked through one predicate, User::maySignIn(), at every
door: sign-in, the web session, API tokens and the two-factor
challenge. An hourly sweep also switches `active` off, so the list,
its filter and seat counts agree. The sweep is not what enforces it,
so a scheduler that is not running cannot keep an account open.

An account cannot be active with a date that has passed. Reactivating
an expired client needs a new date in the same save.

The day-means-end-of-day-where-you-are rule moved out of FileExpiry
into a shared DateInput, so file and account expiry read dates the
same way.

Requested by @Drardollan in #1310.

app/Modules/Platform/Http/Controllers/SchedulerMonitoringController.php

@@ -53,6 +53,7 @@ class SchedulerMonitoringController extends Controller
         return [
             'projectsend:purge-erasures' => (string) __('Purge erased accounts'),
             'projectsend:purge-stale-uploads' => (string) __('Purge stale chunked uploads'),
+            'projectsend:expire-client-accounts' => (string) __('Deactivate expired client accounts'),
             'projectsend:purge-zip-downloads' => (string) __('Purge zip downloads'),
             'projectsend:check-for-updates' => (string) __('Check for updates'),
             'projectsend:fetch-news' => (string) __('Fetch dashboard news'),