Fixes https://github.com/webrecorder/browsertrix/issues/2064
### Changes
- Switches MDE library to one that supports shadow DOM
- Refactors collection components to btrix components
- Fixes collection detail not expanding and contracting correctly
Reorganizes user guide to be more solutions based
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Co-authored-by: Henry Wilkinson <henry@wilkinson.graphics>
Co-authored-by: Emma Segal-Grossman <hi@emma.cafe>
Co-authored-by: Tessa Walsh <tessa@bitarchivist.net>