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/presentation/components/DateText.kt

@@ -5,23 +5,23 @@ import androidx.compose.runtime.remember
 import androidx.compose.ui.platform.LocalContext
 import eu.kanade.domain.ui.UiPreferences
 import eu.kanade.tachiyomi.util.lang.toRelativeString
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.toLocalDateTime
 import tachiyomi.i18n.MR
 import tachiyomi.presentation.core.i18n.stringResource
 import uy.kohesive.injekt.Injekt
 import uy.kohesive.injekt.api.get
-import java.time.Instant
-import java.time.LocalDate
-import java.time.ZoneId
+import kotlin.time.Instant
 
 @Composable
 fun relativeDateText(
     dateEpochMillis: Long,
 ): String {
     return relativeDateText(
-        localDate = LocalDate.ofInstant(
-            Instant.ofEpochMilli(dateEpochMillis),
-            ZoneId.systemDefault(),
-        )
+        localDate = Instant.fromEpochMilliseconds(dateEpochMillis)
+            .toLocalDateTime(TimeZone.currentSystemDefault())
+            .date
             .takeIf { dateEpochMillis != 0L },
     )
 }