Show a confirmation dialog before deleting sources (#185)

## Types of changes

- [ x ] I have read the **CONTRIBUTING** document.
- [ x ] My code follows the code style of this project.
- [ ] I have updated the documentation accordingly.
- [ ] I have added tests to cover my changes.
- [ x ] All new and existing tests passed.
- [ x ] This is **NOT** translation related.

This is implements feature #156

I added a confirmation dialogue which pops up after tapping the delete source button. The popup displays the full name of the source to be deleted and allows the user to decide not to delete the source to prevent erroneous deletions.

I moved most of the logic into the viewholder. Can be easily reverted if you prefer.

All tests pass. I tested correct behavior in emulated versions of android API 25, 34 and 35.

Co-authored-by: Amine <amine.bouabdallaoui@pm.me>
Reviewed-on: #185
Co-authored-by: davidoskky <davidoskky@yahoo.it>
Co-committed-by: davidoskky <davidoskky@yahoo.it>

androidApp/src/main/res/values-in-rID/strings.xml

@@ -129,4 +129,6 @@
     <string name="action_about">"Tentang"</string>
     <string name="marked_as_read">"Membaca item"</string>
     <string name="marked_as_unread">"Item unread"</string>
+    <string name="confirm_delete_title">Confirm Deletion</string>
+    <string name="confirm_delete_message">Are you sure you want to delete the following source?\n%s</string>
 </resources>