Completely remove the legacy hunk table

Summary: Depends on D19056. Fixes T8475. Ref T13054. Merges "ModernHunk" back into "Hunk".

Test Plan: Grepped for `modernhunk`. Reviewed revisions. Created a new revision. Used `bin/differential migrate-hunk` to migrate hunks between storage formats and back.

Maniphest Tasks: T13054, T8475

Differential Revision: https://secure.phabricator.com/D19057

resources/sql/autopatches/20161213.diff.01.hunks.php

@@ -25,9 +25,9 @@ foreach (new LiskRawMigrationIterator($conn, $src_table) as $row) {
     $row['oldLen'],
     $row['newOffset'],
     $row['newLen'],
-    DifferentialModernHunk::DATATYPE_TEXT,
+    DifferentialHunk::DATATYPE_TEXT,
     'utf8',
-    DifferentialModernHunk::DATAFORMAT_RAW,
+    DifferentialHunk::DATAFORMAT_RAW,
     // In rare cases, this could be NULL. See T12090.
     (string)$row['changes'],
     $row['dateCreated'],

resources/sql/autopatches/20180210.hunk.02.renamemodern.sql

@@ -0,0 +1,2 @@
+RENAME TABLE {$NAMESPACE}_differential.differential_hunk_modern
+  TO {$NAMESPACE}_differential.differential_hunk;