[Feature Request] Add Stack Deployment Groups API Specs

[isivaselvan]

Use-cases

StackDeploymentGroups describes below stack-deployment-groups related methods that the HCP Terraform API supports.

• List returns a list of Deployment Groups in a stack.
• Read retrieves a stack deployment group by its ID.
• ReadByName retrieves a stack deployment group by its Name
• ApproveAllPlans approves all pending plans in a stack deployment group.
• Rerun re-runs all the stack deployment runs in a deployment group.

Attempted Solutions

None, Currently not supported

Proposal

Add support for Stack Deployments Groups as a new resource family in python-tfe.

• List Stack Deployment Groups
• Show a Stack deployment group by name
• Show a Stack deployment group by ID
• Approve a Stack deployment group
• Rerun a Stack deployment group
• Add Required Models in src/pytfe/models/stack_deployment_groups.py
• Add Resource in src/pytfe/resources/stack_deployment_groups.py
• Update Client
• Add Examples under examples folder
• Add Unit tests in tests/units

All new code should follow existing project conventions:

• Pydantic v2 models with populate_by_name=True
• alias-based JSON:API field mapping
• _Service base class
• Iterator-based pagination via _list.