Fix Yomitan API not able to export dictionary CSS on Firefox

[Kuuuube]

Partially a regression introduced by #2132
Fixes #2190

1. Bring back CSSOM sanitization removed in Fix problems with CSS nesting in Yomitan API and Anki note data #2132 as a fallback for when the offscreen page is not available. (5ef41f2)
2. CSSOM cannot handle complex CSS and will always fail for some dictionaries on browsers that do not support the offscreen page. Allow users to set yomitanApiAllowCssSanitizationBypass to bypass sanitization.
3. enableYomitanApi uses data-permissions-setting since it has required permissions to be enabled. For some reason permissions settings were never added to the transformation triggers. This is required to only show yomitanApiAllowCssSanitizationBypass when enableYomitanApi is set to true. (1bef193)

Currently, this issue seems to only appear on Firefox. I've limited the visibility of yomitanApiAllowCssSanitizationBypass to Firefox only since it's not something users should have enabled unless really needed.