Remove dependency injection from core module and data module from presentation-widget module

Includes side effects:
- No longer need to restart app for user agent string change to take effect
- parseAs extension function requires a Json instance in the calling context, which doesn't necessarily need to be the default one provided by Injekt

source-api/build.gradle.kts

@@ -10,20 +10,14 @@ android {
     defaultConfig {
         consumerProguardFile("consumer-proguard.pro")
     }
-
 }
 
 dependencies {
-
     implementation(project(":core"))
 
     api(kotlinx.serialization.json)
-
+    api(libs.injekt.core)
     api(libs.rxjava)
-
     api(libs.preferencektx)
-
     api(libs.jsoup)
-
-    implementation(androidx.corektx)
 }