Fix log submission OOM, improve log scrolling.

We were getting a TransactionTooLargeException when giving an
EditText a very large (1.5MB+) text block. This has been resolved
by switching to a RecyclerView to show the text line-by-line. As a
side-effect, this improves scroll performance on lower-end devices.

Also, I added a button to jump to the bottom of the log because I
really wanted one :)

Fixes #8124

res/layout/item_log_preview.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<EditText
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:paddingLeft="10dp"
+    android:paddingRight="10dp"
+    android:typeface="monospace"
+    android:textSize="10sp"
+    android:background="@null"
+    android:inputType="textNoSuggestions|textMultiLine"
+    tools:ignore="SmallSp" />