Replace java.time APIs with kotlin(x).(date)time (#3001)

* Replace java.time APIs with kotlin(x).(date)time

kotlinx-datetime explicitly says in its README that it does not cover
i18n, so we have to stick with using their toJavaX converters wherever
we localise dates and times.

Yes, some of these replacements are... questionable. But I wanted to
try and maximise the replacement for now.

* Bump kotlinx-datetime to 0.8.0

* More kotlin.time/kotlinx-datetime replacements

* Remove redundant init block & make attributes val

* Replace new use of java.time.Instant

app/src/main/java/eu/kanade/domain/manga/interactor/UpdateManga.kt

@@ -1,11 +1,13 @@
 package eu.kanade.domain.manga.interactor
 
+import kotlinx.datetime.LocalDateTime
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.toLocalDateTime
 import tachiyomi.domain.manga.interactor.FetchInterval
 import tachiyomi.domain.manga.model.Manga
 import tachiyomi.domain.manga.model.MangaUpdate
 import tachiyomi.domain.manga.repository.MangaRepository
-import java.time.Instant
-import java.time.ZonedDateTime
+import kotlin.time.Clock
 
 class UpdateManga(
     private val mangaRepository: MangaRepository,
@@ -22,25 +24,31 @@ class UpdateManga(
 
     suspend fun awaitUpdateFetchInterval(
         manga: Manga,
-        dateTime: ZonedDateTime = ZonedDateTime.now(),
-        window: Pair<Long, Long> = fetchInterval.getWindow(dateTime),
+        timeZone: TimeZone = TimeZone.currentSystemDefault(),
+        dateTime: LocalDateTime = Clock.System.now().toLocalDateTime(timeZone),
+        window: Pair<Long, Long> = fetchInterval.getWindow(dateTime.date, timeZone),
     ): Boolean {
         return mangaRepository.update(
-            fetchInterval.toMangaUpdate(manga, dateTime, window),
+            fetchInterval.toMangaUpdate(manga, dateTime, timeZone, window),
         )
     }
 
     suspend fun awaitUpdateLastUpdate(mangaId: Long): Boolean {
-        return mangaRepository.update(MangaUpdate(id = mangaId, lastUpdate = Instant.now().toEpochMilli()))
+        return mangaRepository.update(MangaUpdate(id = mangaId, lastUpdate = Clock.System.now().toEpochMilliseconds()))
     }
 
     suspend fun awaitUpdateCoverLastModified(mangaId: Long): Boolean {
-        return mangaRepository.update(MangaUpdate(id = mangaId, coverLastModified = Instant.now().toEpochMilli()))
+        return mangaRepository.update(
+            MangaUpdate(
+                id = mangaId,
+                coverLastModified = Clock.System.now().toEpochMilliseconds(),
+            ),
+        )
     }
 
     suspend fun awaitUpdateFavorite(mangaId: Long, favorite: Boolean): Boolean {
         val dateAdded = when (favorite) {
-            true -> Instant.now().toEpochMilli()
+            true -> Clock.System.now().toEpochMilliseconds()
             false -> 0
         }
         return mangaRepository.update(