Convert :source-api and :source-local to android library module (#3636)

- There's really no plan to support other platforms on this code base
- The "KMP" modules only had android target which is rather pointless
- `i18n` involves more work but given it has no actual code keeping it as is

source-api/src/androidMain/kotlin/eu/kanade/tachiyomi/source/PreferenceScreen.kt

@@ -1,3 +0,0 @@
-package eu.kanade.tachiyomi.source
-
-actual typealias PreferenceScreen = androidx.preference.PreferenceScreen

source-api/src/commonMain/kotlin/eu/kanade/tachiyomi/source/PreferenceScreen.kt

@@ -1,3 +0,0 @@
-package eu.kanade.tachiyomi.source
-
-expect class PreferenceScreen

source-api/src/commonMain/kotlin/eu/kanade/tachiyomi/util/RxExtension.kt

@@ -1,5 +0,0 @@
-package eu.kanade.tachiyomi.util
-
-import rx.Observable
-
-expect suspend fun <T> Observable<T>.awaitSingle(): T

source-api/src/main/kotlin/eu/kanade/tachiyomi/source/ConfigurableSource.kt

@@ -3,6 +3,7 @@ package eu.kanade.tachiyomi.source
 import android.app.Application
 import android.content.Context
 import android.content.SharedPreferences
+import androidx.preference.PreferenceScreen
 import uy.kohesive.injekt.Injekt
 import uy.kohesive.injekt.api.get
 

source-api/src/main/kotlin/eu/kanade/tachiyomi/util/RxExtension.kt

@@ -3,4 +3,4 @@ package eu.kanade.tachiyomi.util
 import rx.Observable
 import tachiyomi.core.common.util.lang.awaitSingle
 
-actual suspend fun <T> Observable<T>.awaitSingle(): T = awaitSingle()
+suspend fun <T> Observable<T>.awaitSingle(): T = awaitSingle()