Hotfix/offline products caching

[patzick]

Related issues

closes #2543, #2569, #1698

Short description and why it's useful

Things done in this PR:

• Fixed problem with incomplete category products load for offline use - there were two different queries for online and offline use so some visible on category page product weren't cached and caused Incomplete category load for offline mode  #2543 problem
• Category asyncData refactored to async/await
• new products are not pulled in offline mode in category view, this caused crash for all category products in Category page 'crashes' after scrolling down in offline mode.  #2569
• there is new request for SSR render on category page to cache products when first render is category page, closing Populate elasticCache collection after SSR reload #1698
• like in Populate elasticCache collection after SSR reload #1698 products on homepage are cached in SSR view

Upgrade Notes and Changelog

• No upgrade steps required (100% backward compatibility)
• I've updated the Upgrade notes and Changelog on how to port existing VS sites with this new feature

[pkarw]

Overall great job!

Things we need to double check:

• error handling after asyncData refactor: non existing category (should be 404 response), non working elastic (should give us 500 error)
• urldispatcher vs beforeRouteEnter on Category if it doesn’t cause some side effects
• double check if this product/list action isn’t dispatched when browsing solely in CSR from page to page

[pkarw]

@patzick it shouldn’t be category/products executed in beforeRouteEnter because it executed two requests - it should just execute the second one with include/excludeFields set to null - just the caching request. The first request modified current product list which causes blinkin - confirmed on next and demo