Remove the lewis features

[sandbergja]

What maintenance needs to be done?

Remove the Lewis Library "Staff features" and "Patron features" features

Level of urgency

• High
• Moderate
• Low

Why is this maintenance needed?

Lewis is now using the lockers application, and will be for the foreseeable future, so we will not need to turn these features off again. Removing them from the code would simplify it. Thanks @maxkadel for bringing this up.

Acceptance criteria

• The Lewis features are removed
• The application code that consults these feature flags is simplified to assume that they are both always on
• We remove any tests for the cases when these feature flags are off.