LibCore: Make `guess_mime_type_based_on_filename()' recognise CSV files

Author: https://github.com/alimpfard
Commit: https://github.com/SerenityOS/serenity/commit/8066a623d90
Pull-request: https://github.com/SerenityOS/serenity/pull/4149
Issue: https://github.com/SerenityOS/serenity/issues/4010
Issue: https://github.com/SerenityOS/serenity/issues/4136

Libraries/LibCore/MimeData.cpp

@@ -94,6 +94,8 @@ String guess_mime_type_based_on_filename(const StringView& path)
         return "text/html";
     if (path.ends_with("/", CaseSensitivity::CaseInsensitive))
         return "text/html";
+    if (path.ends_with(".csv", CaseSensitivity::CaseInsensitive))
+        return "text/csv";
     return "text/plain";
 }