Migrate our customized _previous_next_doc.html.erb to a view component

[sandbergja]

What maintenance needs to be done?

Migrate our customized _previous_next_doc.html.erb partial to a view component

Level of urgency

• High
• Moderate
• Low

Why is this maintenance needed?

• This partial is deprecated in Blacklight 7 and removed in Blacklight 8

Acceptance criteria

• All the logic and styles of our custom _previous_next_doc.html.erb partial are added to a view component that inherits from a view component in stock blacklight
• We keep _previous_next_doc.html.erb, but all it does is render the new component

Implementation notes, if any

• As of today, Blacklight 8 uses a component named Blacklight::SearchContext::ServerItemPaginationComponent to provide the previous/next doc functionality. Unfortunately, this component has not yet been backported to Blacklight 7. See _previous_next_doc.html.erb deprecation in 7.x should use updated component name projectblacklight/blacklight#3313
• Blacklight 7 does have a component called Blacklight::SearchContextComponent (it's actually the old version of ServerItemPaginationComponent, so it has a similar API), but which is not present in Blacklight 8.

[maxkadel]

Waiting for review of Blacklight backport projectblacklight/blacklight#3421