URLs when categories are selected in Collection Categories Filter should be user friendly

• Type: Story
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: None
• Fix Version/s: None
• Component/s: Fragment Administration, Out of the box Fragments > Collection Display Fragment
• Labels:
  • d_21_06
  • fc_21_07
• Epic Link: Additional sorting & text search options for Collection Displays

The URLs that are generated when a user selects categories in the Collection Categories Filter should change.

Details containing the motivation for that are here: https://docs.google.com/document/d/13Giy5cFJ-sXTOXjCsUULdMVWmaaMTdMmN6LeRD_wPjA/edit?disco=AAAAK7BCZ8Y

Currently the URL parameters are generated as:
?categoryId_<collectionFilterFragmentEntryLinkId>=<assetCategoryId>

Example:
?categoryId_40910=39647&categoryId_40910=39641&categoryId_40913=39663&categoryId_40913=39751&categoryId_40913=39748

There are two improvements to be made:

1) Have one param value for each filter and merge several categories in one filter into one value (to then apply ORs in one case and ANDs in another:

e.g: ?categories_sports=123__or__234&categories_teams=345__or__456&categories_teams2=345__or__789

2) Using more friendly category identifiers instead of ids. For this we can use the category's External Reference Code