Support external repos

Largely taken from SY.

Co-authored-by: jobobby04 <jobobby04@users.noreply.github.com>
(cherry picked from commit c17ada2c98041877ab901efb9b03497130ead34a)

# Conflicts:
#	app/src/main/java/eu/kanade/domain/source/interactor/CreateSourceRepo.kt
#	app/src/main/java/eu/kanade/presentation/browse/ExtensionDetailsScreen.kt
#	app/src/main/java/eu/kanade/presentation/category/SourceRepoScreen.kt
#	app/src/main/java/eu/kanade/presentation/category/components/CategoryDialogs.kt
#	app/src/main/java/eu/kanade/presentation/category/components/repo/SourceRepoContent.kt
#	app/src/main/java/eu/kanade/presentation/more/settings/screen/SettingsBrowseScreen.kt
#	app/src/main/java/eu/kanade/tachiyomi/extension/api/ExtensionGithubApi.kt
#	app/src/main/java/eu/kanade/tachiyomi/extension/model/Extension.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/browse/BrowseSourceScreenModel.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/category/CategoryScreen.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryScreenModel.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaScreenModel.kt

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

@@ -80,4 +80,9 @@
         <item quantity="one">Extension update available</item>
         <item quantity="other">%d extension updates available</item>
     </plurals>
+
+    <plurals name="num_repos">
+        <item quantity="one">%d repo</item>
+        <item quantity="other">%d repos</item>
+    </plurals>
 </resources>

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

@@ -336,6 +336,17 @@
     <string name="ext_installer_shizuku_stopped">Shizuku is not running</string>
     <string name="ext_installer_shizuku_unavailable_dialog">Install and start Shizuku to use Shizuku as extension installer.</string>
 
+    <!-- Extension repos -->
+    <string name="label_extension_repos">Extension repos</string>
+    <string name="information_empty_repos">You have no repos set.</string>
+    <string name="action_add_repo">Add repo</string>
+    <string name="action_add_repo_message">Add additional repos to Tachiyomi, the format of a repo is \"username/repo\", with username being the repo owner, and repo being the repo name.</string>
+    <string name="error_repo_exists">This repo already exists!</string>
+    <string name="action_delete_repo">Delete repo</string>
+    <string name="invalid_repo_name">Invalid repo name</string>
+    <string name="delete_repo_confirmation">Do you wish to delete the repo \"%s\"?</string>
+    <string name="repo_extension_message">This extension is from an external repo. Tap to view the repo.</string>
+
       <!-- Reader section -->
     <string name="pref_fullscreen">Fullscreen</string>
     <string name="pref_show_navigation_mode">Show tap zones overlay</string>