Base model class for Well and Submission models

[lunamoonmoon]

Describe the task
Consider having Well and Submission in backend/wells/models.py extend off a common base class, given that they mostly have the exact same fields

Purpose

• Cleaner code, mentioned in the repo as a comment
• These classes are closely related, but if they are to diverge, it can cause errors

Acceptance Criteria

• Create a base class with the fields used by both well and submission models
• Create a well model which extends off this base and adds unique fields
• Create a submission model which extends off this base and adds unique fields

Additional context

• 
• Would need to look deeper into the inheritance of the classes

[Keegnan]

Unless this becomes an issue, we are unlikely to address it. Will reconsider if anything changes.