Introduce ktor http client with okhttp backend

app/src/main/java/com/hippo/ehviewer/EhApplication.kt

@@ -55,6 +55,8 @@ import com.hippo.yorozuya.IntIdGenerator
 import eu.kanade.tachiyomi.core.preference.AndroidPreferenceStore
 import eu.kanade.tachiyomi.ui.reader.setting.ReaderPreferences
 import eu.kanade.tachiyomi.util.lang.launchIO
+import io.ktor.client.HttpClient
+import io.ktor.client.engine.okhttp.OkHttp
 import kotlinx.coroutines.DelicateCoroutinesApi
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
@@ -312,6 +314,14 @@ class EhApplication : Application(), DefaultLifecycleObserver, ImageLoaderFactor
             builder.build()
         }
 
+        val ktorClient by lazy {
+            HttpClient(OkHttp) {
+                engine {
+                    preconfigured = okHttpClient
+                }
+            }
+        }
+
         @JvmStatic
         val galleryDetailCache by lazy {
             LruCache<Long, GalleryDetail>(25).also {