Bitbucket support

[mzueva]

Background Cloud Pipeline shall support Bitbucket as VCS for pipelines and version storages.

Target Bitbucket API version - 7.17

[ekazachkova]

The following actions are not supported for bitbucket repositories (due to Bitbucket Server API does not support file deletion):

• DELETE pipeline/{id}/file
• DELETE pipeline/{id}/folder
• POST pipeline/{id}/folder (when previousPath is not empty)
• POST pipeline/{id}/file (when previousPath is not empty)
• POST pipeline/{id}/files (when previousPath is not empty)

All this methods will return UnsupportedOperationException.

@rodichenko Could you please handle such situations?