Create enum for session end states and event results

[areibman]

🚀 Feature Request

💡 Got a brilliant idea?
Currently, session end states and event results are hard coded as strings instead of typed enums. These results should be success, indeterminate, and fail

Instead, we are inconsistent with database entries. Sessions, for example:

and Events:

🤔 Is your feature request related to a problem?
N/A

🎉 Describe the solution you'd like
We'd like to create an enum for the possible result states for:

1. Sessions
2. Events