Refactor notifications to Kotlin & paging (#4026)

This refactors the NotificationsFragment and related classes to Kotlin &
paging.
While trying to preserve as much of the original behavior as possible,
this adds the following improvements as well:
- The "show notifications filter" preference was added again
- The "load more" button now has a background ripple effect when clicked
- The "legal" report category of Mastodon 4.2 is now supported in report
notifications
- Unknown notifications now display "unknown notification type" instead
of an empty line

Other code quality improvements:
- All views from xml layouts are now referenced via ViewBindings
- the classes responsible for showing system notifications were moved to
a new package `systemnotifications` while the classes from this
refactoring are in `notifications`
- the id of the local Tusky account is now called `tuskyAccountId` in
all places I could find

closes https://github.com/tuskyapp/Tusky/issues/3429

---------

Co-authored-by: Zongle Wang <wangzongler@gmail.com>

app/src/main/java/com/keylesspalace/tusky/entity/Notification.kt

@@ -75,7 +75,6 @@ data class Notification(
         REPORT("admin.report", R.string.notification_report_name);
 
         companion object {
-            @JvmStatic
             fun byString(s: String): Type {
                 return entries.firstOrNull { it.presentation == s } ?: UNKNOWN
             }
@@ -85,25 +84,9 @@ data class Notification(
                 listOf(MENTION, REBLOG, FAVOURITE, FOLLOW, FOLLOW_REQUEST, POLL, STATUS, SIGN_UP, UPDATE, REPORT)
         }
 
-        override fun toString(): String {
-            return presentation
-        }
+        override fun toString() = presentation
     }
 
-    override fun hashCode(): Int {
-        return id.hashCode()
-    }
-
-    override fun equals(other: Any?): Boolean {
-        if (other !is Notification) {
-            return false
-        }
-        return other.id == this.id
-    }
-
-    /** Helper for Java */
-    fun copyWithStatus(status: Status?): Notification = copy(status = status)
-
     // for Pleroma compatibility that uses Mention type
     fun rewriteToStatusTypeIfNeeded(accountId: String): Notification {
         if (type == Type.MENTION && status != null) {

app/src/main/java/com/keylesspalace/tusky/entity/Status.kt

@@ -47,7 +47,7 @@ data class Status(
     @Json(name = "media_attachments") val attachments: List<Attachment>,
     val mentions: List<Mention>,
     // Use null to mark the absence of tags because of semantic differences in LinkHelper
-    val tags: List<HashTag>? = null,
+    val tags: List<HashTag> = emptyList(),
     val application: Application? = null,
     val pinned: Boolean = false,
     val muted: Boolean = false,
@@ -66,13 +66,6 @@ data class Status(
     val actionableStatus: Status
         get() = reblog ?: this
 
-    /** Helpers for Java */
-    fun copyWithFavourited(favourited: Boolean): Status = copy(favourited = favourited)
-    fun copyWithReblogged(reblogged: Boolean): Status = copy(reblogged = reblogged)
-    fun copyWithBookmarked(bookmarked: Boolean): Status = copy(bookmarked = bookmarked)
-    fun copyWithPoll(poll: Poll?): Status = copy(poll = poll)
-    fun copyWithPinned(pinned: Boolean): Status = copy(pinned = pinned)
-
     @JsonClass(generateAdapter = false)
     enum class Visibility(val num: Int) {
         UNKNOWN(0),