Caching toots (#809)

* Initial timeline cache implementation

* Fix build/DI errors for caching

* Rename timeline entities tables. Add migration. Add DB scheme file.

* Fix uniqueness problem, change offline strategy, improve mapping

* Try to merge in new statuses, fix bottom loading, fix saving spans.

* Fix reblogs IDs, fix inserting elements from top

* Send one more request to get latest timeline statuses

* Give Timeline placeholders string id. Rewrite Either in Kotlin

* Initial placeholder implementation for caching

* Fix crash on removing overlap statuses

* Migrate counters to long

* Remove unused counters. Add minimal TimelineDAOTest

* Fix bug with placeholder ID

* Update cache in response to events. Refactor TimelineCases

* Fix crash, reduce number of placeholders

* Fix crash, fix filtering, improve placeholder handling

* Fix migration, add 8-9 migration test

* Fix initial timeline update, remove more placeholders

* Add cleanup for old statuses

* Fix cleanup

* Delete ExampleInstrumentedTest

* Improve timeline UX regarding caching

* Fix typos

* Fix initial timeline update

* Cleanup/fix initial timeline update

* Workaround for weird behavior of first post on initial tl update.

* Change counter types back to int

* Clear timeline cache on logout

* Fix loading when timeline is completely empty

* Fix androidx migration issues

* Fix tests

* Apply caching feedback

* Save account emojis to cache

* Fix warnings and bugs

app/src/androidTest/java/com/keylesspalace/tusky/ExampleInstrumentedTest.java

@@ -1,26 +0,0 @@
-package com.keylesspalace.tusky;
-
-import android.content.Context;
-import androidx.test.InstrumentationRegistry;
-import androidx.test.runner.AndroidJUnit4;
-
-import org.junit.Test;
-import org.junit.runner.RunWith;
-
-import static org.junit.Assert.*;
-
-/**
- * Instrumentation test, which will execute on an Android device.
- *
- * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
- */
-@RunWith(AndroidJUnit4.class)
-public class ExampleInstrumentedTest {
-    @Test
-    public void useAppContext() throws Exception {
-        // Context of the app under test.
-        Context appContext = InstrumentationRegistry.getTargetContext();
-
-        assertEquals("com.keylesspalace.tusky", appContext.getPackageName());
-    }
-}