Create a BitBucket Pipeline for ORT

[tsteenbe]

BitBucket seems to used by various governments and whether ORT can be run in BitBucket has come up in multiple conversations. Filling this ticket so we have one place to collect information and track development of ORT supporting BitBucket.

Documentation: https://support.atlassian.com/bitbucket-cloud/resources/ => Build, test, and deploy with Pipelines

[stschroeder]

Just a tiny hint: #2441 needs to be done first if you want to serve ORT via a Docker image. Bitbucket does not have support to create a Docker container on the fly using a Dockerfile as Jenkins does, see Configure bitbucket-pipelines.yml.

[tsteenbe]

@stschroeder Would you be interest to help develop a BitBucket Pipeline for ORT?