org.lichess.mobileapp.free: add Lichess app

• The app complies with the inclusion criteria
• The original app author has been notified (and does not oppose the inclusion)
  • If you are not the author, please paste the link of the reply from the author: https://github.com/lichess-org/lichobile/issues/409#issuecomment-243370292
• All related fdroiddata and RFP issues have been referenced in this merge request
• The upstream app source code repo contains the app metadata (summary/description/images/changelog/etc) in a Fastlane or Triple-T folder structure
  • If you are the author, please do add metadata in your repo; If you are not the author, please at least open an issue upstream for the metadata: Fastlane is not upstreamed yet, but it's in progress: https://github.com/lichess-org/lichobile/pull/2185 .
• Builds with fdroid build
• Releases are tagged

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Closes rfp#1853 (closed)

Closes #227 (closed)

cc @IzzySoft