fix: Disable dark mode from sites that already respect prefers-color-scheme dark

[karthikeyansundaram2]

Summary

Closes #34

Addresses: Disable dark mode from sites that already respect prefers-color-scheme dark

Changes

 _locales/en/messages.json               |  3 ++
 content-scripts/filters.js              | 50 +++++++++++++++++++++++++++++++++
 options-page/skeleton-parts/schedule.js | 12 ++++++++
 3 files changed, 65 insertions(+)

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Contribution by @karthikeyansundaram2