Add caching on the final Suggestion results array

Problem/Motivation

At the moment we keep on Drupal cache the SOLR suggestion for each suggested term (phrase).
It would be nice to have an option on the module config to enable caching on the final Suggestions array after the removals and count fixes.
This way we could save some memory from Drupal while returning the results.

Remaining tasks

- Create the caching plugin on Drupal
- Create the new config on module (yml, UI)
- Decide how should we cache results (tags, time limit etc)
- Decide when and how we clean or update the cached results
- Decide how should we manage the main module (search_api_autocomplete) config of the limit on results (e.g. what if we should return up to 20 results but the final results after removals are 12? Should we update the main module count limit again until we reach the 20 results?)