perf: optimize loading messages in threads (#552)

* perf: improve lazy loading and remove spinner

* perf: optimize message loading by caching and reducing queries

* docs: update changelog

* style: use constant for cache size

* refactor: minor consistency improvement

* fix: override loaded preview size

* refactor: streamline message loading logic in scroll listener

* refactor: organize some dedup related code

* build: bump detekt return count limit

2 is 2 low

* fix: check contacts permissions before registering observer

* fix: disable fetching media resolutions in threads

* refactor: remove resolution fetching related code

* perf: cache MMS thread participants

* refactor: remove unused BitmapFactory import

* fix: invalidate participants cache when necessary

* fix: return copied participants from cache

* fix: adjust image loading dimensions in threads

* fix: use stable ids for header items

* fix: always rely on database check before flipping `allMessagesFetched`

app/src/main/kotlin/org/fossify/messages/App.kt

@@ -1,7 +1,38 @@
 package org.fossify.messages
 
+import android.database.ContentObserver
+import android.net.Uri
+import android.os.Handler
+import android.os.Looper
+import android.provider.ContactsContract
 import org.fossify.commons.FossifyApp
+import org.fossify.commons.extensions.hasPermission
+import org.fossify.commons.helpers.PERMISSION_READ_CONTACTS
+import org.fossify.messages.helpers.MessagingCache
 
 class App : FossifyApp() {
     override val isAppLockFeatureAvailable = true
+
+    override fun onCreate() {
+        super.onCreate()
+        if (hasPermission(PERMISSION_READ_CONTACTS)) {
+            listOf(
+                ContactsContract.Contacts.CONTENT_URI,
+                ContactsContract.Data.CONTENT_URI,
+                ContactsContract.DisplayPhoto.CONTENT_URI
+            ).forEach {
+                try {
+                    contentResolver.registerContentObserver(it, true, contactsObserver)
+                } catch (_: Exception){
+                }
+            }
+        }
+    }
+
+    private val contactsObserver = object : ContentObserver(Handler(Looper.getMainLooper())) {
+        override fun onChange(selfChange: Boolean, uri: Uri?) {
+            MessagingCache.namePhoto.evictAll()
+            MessagingCache.participantsCache.evictAll()
+        }
+    }
 }