Nextcloud 32/33 Compatibility: Remove deprecated API usage

This commit updates the SnappyMail integration app for Nextcloud to support version 32 and the upcoming version 33.

Key changes:
- Updated `info.xml` to allow `max-version="33"`.
- Refactored `AdminSettings`, `Application`, `FetchController`, `PageController`, `Settings` (command), and `InstallStep` to use Dependency Injection instead of the deprecated `\OC::$server` service container.
- Replaced deprecated `OC_User`, `OC_Util` (e.g. `addScript`), and `OC_App` calls with their `OCP` (public API) counterparts or modern equivalents.
- Updated `SnappyMailHelper` to use `\OCP\Server::get()` for static context access where DI is not possible.
- Moved script and style registration from Controllers (using deprecated `Util::addScript`) to templates using `script()` and `style()` helpers.
- Updated `Settings` console command to extend `Symfony\Component\Console\Command\Command` instead of deprecated `OC\Core\Command\Base`.
- Addressed PHP 8.4+ compatibility by adding explicit property types and nullable types where necessary in the integration code.

Co-authored-by: nextgen-networks <21206978+nextgen-networks@users.noreply.github.com>

plugins/cache-redis/Predis/Connection/RelayMethods.php

@@ -32,7 +32,7 @@ trait RelayMethods
      * @param  string   $pattern
      * @return bool
      */
-    public function onInvalidated(?callable $callback, ?string $pattern = null)
+    public function onInvalidated(?callable $callback, string $pattern = null)
     {
         return $this->client->onInvalidated($callback, $pattern);
     }
@@ -129,7 +129,7 @@ trait RelayMethods
      * @param  ?int    $db
      * @return bool
      */
-    public function flushMemory(?string $endpointId = null, ?int $db = null)
+    public function flushMemory(string $endpointId = null, int $db = null)
     {
         return $this->client->flushMemory($endpointId, $db);
     }