refactor: abstract XML parser output operations

[jesperhodge]

• fix: question parser
• fix: add class olx_description and parse html with this class back to description tag
• refactor: abstract out operations on XML parser output and add fine-grained tests

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (6945234) 90.57% compared to head (970808f) 90.62%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #445 +/- ## ========================================== + Coverage 90.57% 90.62% +0.04% ========================================== Files 227 228 +1 Lines 4129 4151 +22 Branches 831 839 +8 ========================================== + Hits 3740 3762 +22 Misses 369 369 Partials 20 20 ```

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