Implement time ago parser and improve localization handling

- Handle special cases for languages where the number is not shown
- Rework the Downloader base implementation, allowing for more
advanced things to be done
- Separate the localization from the content country (just like
YouTube let's the user choose both).

timeago-parser/build.gradle

@@ -1,3 +1,6 @@
 dependencies {
     testImplementation 'junit:junit:4.12'
+
+    implementation 'com.grack:nanojson:1.1'
+    implementation 'com.github.spotbugs:spotbugs-annotations:3.1.0'
 }