new port: security/omniauth-bitbucket

Ruby gem to add an OmniAuth strategy for Atlassian Bitbucket.

WWW: https://github.com/sishen/omniauth-bitbucket

PR: 199780
Differential Revision: https://reviews.freebsd.org/D2467
Submitted by: Torsten Zuehlsdorff <ports@toco-domains.de>
Approved by: swills (mentor), mat (mentor)