Add Keybase integration (#10297)

* create account_identity_proofs table

* add endpoint for keybase to check local proofs

* add async task to update validity and liveness of proofs from keybase

* first pass keybase proof CRUD

* second pass keybase proof creation

* clean up proof list and add badges

* add avatar url to keybase api

* Always highlight the “Identity Proofs” navigation item when interacting with proofs.

* Update translations.

* Add profile URL.

* Reorder proofs.

* Add proofs to bio.

* Update settings/identity_proofs front-end.

* Use `link_to`.

* Only encode query params if they exist.

URLs without params had a trailing `?`.

* Only show live proofs.

* change valid to active in proof list and update liveness before displaying

* minor fixes

* add keybase config at well-known path

* extremely naive feature flagging off the identity proof UI

* fixes for rubocop

* make identity proofs page resilient to potential keybase issues

* normalize i18n

* tweaks for brakeman

* remove two unused translations

* cleanup and add more localizations

* make keybase_contacts an admin setting

* fix ExternalProofService my_domain

* use Addressable::URI in identity proofs

* use active model serializer for keybase proof config

* more cleanup of keybase proof config

* rename proof is_valid and is_live to proof_valid and proof_live

* cleanup

* assorted tweaks for more robust communication with keybase

* Clean up

* Small fixes

* Display verified identity identically to verified links

* Clean up unused CSS

* Add caching for Keybase avatar URLs

* Remove keybase_contacts setting