Removes the ACL populate restrictions from `App Settings` and `App
Customization` content types. They are not needed for security, because
the types do not contain relations. Having them needlessly
complicates adding new settings, because each component needs to be
explicitly allowed to be populated.

Add proper typing to the Strapi functions handling `DynamicSettings` and
add null checks to prevent errors if the initial `App Settings` object
was not created correctly.

A PoC of the stacked context paradigm where any edits are reset by the
consuming component’s `onDestroy` lifecycle hook.

The example sets the page background using both `+page`s and `+layout`s:

1. /(voters)/+layout: init the context with default bg-base-100
2. /(voters)/+page: base-300 for the front page
3. /questions/+layout: base-300 for the whole questions route
4. /questions/[categoryId]/+page base-100 for just the category intro
   pages
5. /(voters)/results/[entityType]/[entityId]/+page base-300 for the
   entity detail page

NB. Ultimately, we would init the context in `/+layout` but we're
making changes now only to the Voter App.