Add settings for max days in next up (#850)

## Description
Add a settings to set the maximum amount of time items can appear in
Next Up.

Options range from 7 days to a year, or no limit (current & default
behavior)

### Related issues
Closes #662 

### Testing
Tested on the emulator and verified URLs, added unit tests

## Screenshots
N/A, just a new slider bar setting

## AI or LLM usage
None

app/src/main/java/com/github/damontecres/wholphin/ui/main/HomeViewModel.kt

@@ -98,6 +98,7 @@ class HomeViewModel
                                 limit,
                                 prefs.enableRewatchingNextUp,
                                 false,
+                                prefs.maxDaysNextUp,
                             )
                         val watching =
                             buildList {

app/src/main/java/com/github/damontecres/wholphin/ui/preferences/SliderPreference.kt

@@ -65,7 +65,7 @@ fun SliderPreference(
         }
 
         Row(
-            horizontalArrangement = Arrangement.spacedBy(8.dp),
+            horizontalArrangement = Arrangement.spacedBy(16.dp),
             verticalAlignment = Alignment.CenterVertically,
             modifier =
                 Modifier