Thank you for voting on this suggestion. In Bitbucket Data Center 7.18 we've added HTTP Access Tokens for projects and repositories. More details can be found in the release notes and official documentation.
For those who are looking for the OAuth 2.0, please vote fo the ticket -
It is inconvenient and in some cases not viable from a security standpoint to use password based authentication to access Bitbucket (eg for REST calls from scripts, CI systems and other tooling).
Provide the possibility to authenticate via HTTP using a token based mechanism (possibly OAuth).