Add BGInstances access to RollStatus

[gru1960]

Blue and Green Instance Metadata and Status from the RollStatus API should be exposed to the golang sdk layer

Checklist:

• [ ] I have filled relevant self assessment (NodeJS, Frontend, Backend)
• [ ] I have run ESlint on my changes and fixed all warnings and errors (NodeJS & Frontend Services)
• [ ] My code follows the style guidelines of this project
• [ ] I have performed a self-review of my own code
• [ ] I have validated all the requirements in the Jira task were answered
• [ ] I have all neccessary approvals for the design/mini design of this task
• [ ] I have approved the API changes and granular permission patterns (documentation subtask) (For public services only)

[sharadkesarwani]

Code in PR is missing other attributes in API response, so we have added those too and merged into main with separate PR hence closing this one.