Add an API to fetch the status of the migration

[kalroy]

User Story

As an Automate User, I should be able to fetch the status of the latest migration given a migration id

Acceptance Criteria

• The API should return status In Progress or Completed
• The API should always check for the latest migration

Implementation Details

• Add an API accessible externally
• Run a query on the migration table using server id, sort based on id and take the topmost row
• Probable JSON response structure:

{
   "organisation_migration": <status>,
   "user_migration": <status>,   
}

Definition of Done

• All things specified in User Story Acceptance Criteria should be fulfilled.
• All Exceptions are Handled Properly
• Ensure logs have no unnecessary data.
• Test coverage for the new feature is done to at least 70%
• If needed raise Docs PR and tag documentation.
• Swagger Documentation updated
• Smoke Test done.
• Ensure Build and Integration Pipelines are Green.
• PR has 2 approvers.
• All Code Review Comments are Resolved.
• README doc should be updated, if needed.