Fix various MySQL version issues with new charset stuff

Summary:
Ref T1191. Notable stuff:

  - Adds `--disable-utf8mb4` to `bin/storage` to make it easier to test what things will (approximately) do on old MySQL. This isn't 100% perfect but should catch all the major stuff. It basically makes us pretend the server is an old server.
  - Require utf8mb4 to dump a quickstart.
  - Fix some issues with quickstart generation, notably special casing the FULLTEXT handling.
  - Add an `--unsafe` flag to `bin/storage adjust` to let it truncate data to fix schemata.
  - Fix some old patches which don't work if the default table charset is utf8mb4.

Test Plan:
  - Dumped a quickstart.
  - Loaded the quickstart with utf8mb4.
  - Loaded the quickstart with `--disable-utf8mb4` (verified that we get binary columns, etc).
  - Adjusted schema with `--disable-utf8mb4` (got a long adjustment with binary columns, some truncation stuff with weird edge case test data).
  - Adjusted schema with `--disable-utf8mb4 --unsafe` (got truncations and clean adjust).
  - Adjusted schema back without `--disable-utf8mb4` (got a long adjustment with utf8mb4 columns, some invalid data on truncated utf8).
  - Adjusted schema without `--disable-utf8mb4`, but with `--unsafe` (got truncations on the invalid data).

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T1191

Differential Revision: https://secure.phabricator.com/D10757

scripts/sql/manage_storage.php

@@ -64,6 +64,13 @@ try {
         'help'  => 'Do not actually change anything, just show what would be '.
                    'changed.',
       ),
+      array(
+        'name' => 'disable-utf8mb4',
+        'help' => pht(
+          'Disable utf8mb4, even if the database supports it. This is an '.
+          'advanced feature used for testing changes to Phabricator; you '.
+          'should not normally use this flag.'),
+      )
     ));
 } catch (PhutilArgumentUsageException $ex) {
   $args->printUsageException($ex);
@@ -126,6 +133,7 @@ $api->setHost($default_host);
 $api->setPort($default_port);
 $api->setPassword($password);
 $api->setNamespace($args->getArg('namespace'));
+$api->setDisableUTF8MB4($args->getArg('disable-utf8mb4'));
 
 try {
   queryfx(