Add startpage.com as option and default search engine

[SpecialAro]

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Description of Change

Add startpage.com as option and default search engine

Motivation and Context

Add startpage.com as option and default search engine. This is a step forward for #240, this PR is missing the addition of "Other Engines" not on the list, as proposed by @vraravam (maybe you can contribute on this? 🙏).

Screenshots

Checklist

• My pull request is properly named
• The changes respect the code style of the project (npm run prepare-code)
• npm test passes
• I tested/previewed my changes locally

Release Notes

Add startpage.com as option and default search engine