Add configuration for what views to show

[zyteka]

For each user study, we may only want to test a subset of explanation types.

There should be an easy way for someone without familiarity with the front-end code to add/remove explanation types from the sidebar. For example, by updating a top-level config file.

[ghost]

@zyteka Are the other available routes (except /details - which will be always visible as I understand) configurable at a previous step? Do we have BE information about these configuration options, which routes should/shouldn't be available?

Based on your last sentence, at this moment, should we show only the Details page? Thank you.