Fix crash with no planners saved to account

[js0mmer]

Description

• Roadmap page would crash for new users who have no roadmap saved to their account
• adjusted return type of the roadmap route to be undefined when there are no saved planners, frontend code expects undefined to be returned if the user has no saved roadmap
  • was previously returning object with empty arrays of planners, transfers, and undefined timestamp
• fixed another issue where you couldn't save to your account with no transferred courses
• fixed import transcript crash due to different quarter name
• convert any legacy local roadmaps to current data format to prevent any possible crashes there

Steps to verify/test this change:

• Verify changes work as expected on staging instance

Final Checks:

• Verify successful deployment

(optional)

• Write tests
• Write documentation

Issues

Closes #502