OAuth Provider for Atlassian.

[jonasfroeller]

I am currently working on the pr.

[jonasfroeller]

I am currently unable to create a bitbucket workspace... (https://support.atlassian.com/bitbucket-cloud/docs/use-oauth-on-bitbucket-cloud, https://developer.atlassian.com/cloud/bitbucket/oauth-2, https://developer.atlassian.com/cloud/bitbucket/rest/intro/#oauth-2-0, https://developer.atlassian.com/cloud/bitbucket/modules/oauth-consumer, https://confluence.atlassian.com/bitbucketserver/bitbucket-oauth-2-0-provider-api-1108483661.html).
I think Atlassian makes more sense anyways tho.