Adding Bootstrap stage

This PR is adding a new bootstrap stage for the pipelines. This change is related to this MR

Some of the new R3 services like WKS and Schema will require a bootstrapping job to be triggered after deployment, this job will execute some python scripts in order to upload some mapping files/schemas to appropriate CSP storage. These mappings/schemas are not just scoped for integration tests and need to be persisted for proper functioning of the services.

Hence having a separate stage for bootstrap seems more appropriate

@divido @danielscholl @dkodeih @ethiraj @gramdas @osdu/platform/roles/azure-contributors