Don't make install permission required during onboarding

Closes #10257

We show a warning banner in the extensions list and also rely on the system
alert popup if someone attempts to install without the permission already
granted.

(cherry picked from commit f0710df35696c1f6cf7bb5371dfd6ad91d53fae1)

i18n/src/commonMain/resources/MR/base/strings.xml

@@ -183,8 +183,6 @@
     <string name="onboarding_storage_info">Select a folder where %1$s will store chapter downloads, backups, and more.\n\nA dedicated folder is recommended.\n\nSelected folder: %2$s</string>
     <string name="onboarding_storage_action_select">Select a folder</string>
     <string name="onboarding_storage_selection_required">A folder must be selected</string>
-    <string name="onboarding_permission_type_required">Required</string>
-    <string name="onboarding_permission_type_optional">Optional</string>
     <string name="onboarding_permission_install_apps">Install apps permission</string>
     <string name="onboarding_permission_install_apps_description">To install source extensions.</string>
     <string name="onboarding_permission_notifications">Notification permission</string>
@@ -329,6 +327,7 @@
     <string name="ext_info_age_rating">Age rating</string>
     <string name="ext_nsfw_short">18+</string>
     <string name="ext_nsfw_warning">Sources from this extension may contain NSFW (18+) content</string>
+    <string name="ext_permission_install_apps_warning">Permissions are needed to install extensions. Tap here to grant.</string>
     <string name="ext_install_service_notif">Installing extension…</string>
     <string name="ext_installer_pref">Installer</string>
     <string name="ext_installer_legacy">Legacy</string>