Add global TLS verification skip setting

Adds a new boolean setting in the Advanced settings group that allows
users to globally skip TLS certificate verification for all enhanced
apps. This is useful for users who have self-signed certificates on
their services.

When enabled, the Guzzle HTTP client will set 'verify' => false for
all API requests made by enhanced apps.

Resolves linuxserver/Heimdall-Apps#687

lang/en/app.php

@@ -33,6 +33,7 @@ return array (
   'settings.folders' => 'Folders',
   'settings.tags' => 'Tags',
   'settings.categories' => 'Categories',
+  'settings.skip_tls_verification' => 'Skip TLS Verification (for self-signed certificates)',
   'options.none' => '- not set -',
   'options.google' => 'Google',
   'options.ddg' => 'DuckDuckGo',