Change hardcoded strings in the language search dialog to messages

Another comment: While working on this, I also noticed that
"Recent Searches" is hardcoded in the XML file, and
I'm not sure where does it actually appear. I fixed it, too,
but perhaps it can be completely removed.

Fixes #6439.

Author: amire80

app/src/main/res/layout/dialog_select_language.xml

@@ -12,7 +12,7 @@
     android:layout_marginStart="8dp"
     android:layout_marginTop="8dp"
     android:layout_marginEnd="8dp"
-    android:hint="Type Language Name"
+    android:hint="@string/language_search_type_language_name"
     android:padding="12dp"
     app:layout_constraintEnd_toEndOf="parent"
     app:layout_constraintStart_toStartOf="parent"
@@ -22,7 +22,7 @@
     android:id="@+id/recent_searches"
     android:layout_width="0dp"
     android:layout_height="wrap_content"
-    android:text="Recent Searches"
+    android:text="@string/language_search_recent_searches"
     app:layout_constraintTop_toBottomOf="@id/search_language"
     app:layout_constraintEnd_toEndOf="@+id/language_history_list"
     android:layout_marginEnd="8dp"
@@ -55,7 +55,7 @@
     android:id="@+id/all_languages"
     android:layout_width="0dp"
     android:layout_height="wrap_content"
-    android:text="All Languages"
+    android:text="@string/language_search_all_languages"
     app:layout_constraintTop_toBottomOf="@id/separator"
     app:layout_constraintEnd_toEndOf="@+id/language_history_list"
     android:layout_margin="8dp"

app/src/main/res/values-qq/strings.xml

@@ -97,6 +97,9 @@
   <string name="no_uploads_yet">Message shown on contribution list during non-first sync if no uploads present.</string>
   <string name="menu_retry_upload">Menu item text prompting user to retry a failed upload.\n{{Identical|Retry}}</string>
   <string name="menu_cancel_upload">Menu item text prompting user to cancel and delete a failed upload.\n{{Identical|Cancel}}</string>
+  <string name="language_search_type_language_name">Placeholder text in the top search box in the language search dialog.</string>
+  <string name="language_search_recent_searches">A title in the language search dialog.</string>
+  <string name="language_search_all_languages">A title in the language search dialog.</string>
   <string name="menu_download">Menu item text prompting user to download a selected photo or media file locally.\n{{Identical|Download}}</string>
   <string name="preference_license">{{Identical|License}}</string>
   <string name="use_previous">This is a button text. Concise wording is preferred (e.g. \"&amp;\" instead of \"and\"), where possible. It should ideally be rendered in one line, even on small devices.</string>

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

@@ -150,6 +150,9 @@
   <string name="no_uploads_yet">You have not yet uploaded any photos.</string>
   <string name="menu_retry_upload">Retry</string>
   <string name="menu_cancel_upload">Cancel</string>
+  <string name="language_search_type_language_name">Type Language Name</string>
+  <string name="language_search_recent_searches">Recent Searches</string>
+  <string name="language_search_all_languages">All Languages</string>
   <string name="media_upload_policy">By submitting this picture, I declare that this is my own work, that it does not contain copyrighted material or selfies, and otherwise adheres to &lt;a href=\"https://commons.wikimedia.org/wiki/Commons:Policies_and_guidelines\"&gt;Wikimedia Commons policies&lt;/a&gt;.</string>
   <string name="menu_download">Download</string>
   <string name="preference_license">Default License</string>