Honor input-purpose PIN

Otherwise e.g. SIM pins are requested with a numerical keyboard.

src/data/loading.rs

@@ -168,6 +168,7 @@ fn get_directory_string(
         None => match content_purpose {
             ContentPurpose::Number => Special("number"),
             ContentPurpose::Digits => Special("number"),
+            ContentPurpose::Pin => Special("number"),
             ContentPurpose::Phone => Special("number"),
             ContentPurpose::Terminal => Special("terminal"),
             _ => Default,