Add support for AF.

app/src/main/res/values/arrays.xml

@@ -4,6 +4,7 @@
   <string-array name="language_entries">
 <!-- zz --><item>@string/preferences__system_default</item>
 <!-- en --><item>English</item>
+<!-- af --><item>Afrikaans</item>
 <!-- ar --><item>Arabic العربية</item>
 <!-- az --><item>Azərbaycan</item>
 <!-- jv --><item>Basa Jawa</item>
@@ -86,6 +87,7 @@
   <string-array name="language_values">
       <item>zz</item>
       <item>en</item>
+      <item>af</item>
       <item>ar</item>
       <item>az</item>
       <item>jv</item>

app/src/test/java/org/thoughtcrime/securesms/util/dynamiclanguage/LocaleParserTest.java

@@ -42,7 +42,7 @@ public final class LocaleParserTest {
   }
 
   private static String getUnsupportedLanguage() {
-    String unsupportedLanguage = "af";
+    String unsupportedLanguage = "ae";
     assertFalse("Language should be an unsupported one", buildConfigLanguages().contains(unsupportedLanguage));
     return unsupportedLanguage;
   }