Vault: user_domain_id/name and project_domain_id/name implementation for dynamic users

[artem-lifshits]

Implementation of user_domain_id/name and project_domain_id/name for dynamic users. Changes include:

• path_roles.go
• path_roles_test.go
• api.md
• path_creds.go
• path_creds_test.go
• tests for new parameters

[artem-lifshits]

recheck

[artem-lifshits]

regate

[otc-zuul[bot]]

Build succeeded. https://zuul.otc-service.com/t/eco/buildset/6fa6d3bf6e834ae4b186b1bc09d02311

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