Use ItemSortBy constants instead of hardcoded strings

[nielsvanvelzen]

I wanted to check if all sort fields we use in the app were added in jellyfin/jellyfin#7492. Noticed that we don't always use the constants from the apiclient (yeah sorry SDK doesn't have them :p).

Changes

• Use ItemSortBy constants instead of hardcoded strings
• Use "SortName" instead of non-existing "Number" sort field in Live TV
  • I looked at the usages of the value and it's actually always compared with the DatePlayed value, so we could even put gibberish in here. I chose SortName because there is one place where it uses SortName if the value is not DatePlayed

Issues