Add parsing for ssh options (-o) which are passed when using GIT v2 wire protocol by git command (SSH transport)

Summary:
Makes `ssh-connect` compatible with Git v2 wire protocol over SSH

More details about git V2 wire: https://opensource.googleblog.com/2018/05/introducing-git-protocol-version-2.html

`git` command (2.18+) passes extra options (`-o "SendEnv GIT_PROTOCOL"`) to underlying `ssh` command to enable v2 wire protocol (environment variable enabling new protocol).

Phabricator `ssh-connect` command doesn't understand `-o` options and interprets it as host parts hence when you enable git v2 all clones/ls-remotes crash with:
```
#0 ExecFuture::resolvex() called at [<phabricator>/src/applications/repository/storage/PhabricatorRepository.php:525]
#1 PhabricatorRepository::execxRemoteCommand(string, PhutilOpaqueEnvelope) called at [<phabricator>/src/applications/repository/engine/PhabricatorRepositoryPullEngine.php:400]
#2 PhabricatorRepositoryPullEngine::loadGitRemoteRefs(PhabricatorRepository) called at [<phabricator>/src/applications/repository/engine/PhabricatorRepositoryPullEngine.php:343]
#3 PhabricatorRepositoryPullEngine::executeGitUpdate() called at [<phabricator>/src/applications/repository/engine/PhabricatorRepositoryPullEngine.php:126]
phacility#4 PhabricatorRepositoryPullEngine::pullRepositoryWithLock() called at [<phabricator>/src/applications/repository/engine/PhabricatorRepositoryPullEngine.php:40]
phacility#5 PhabricatorRepositoryPullEngine::pullRepository() called at [<phabricator>/src/applications/repository/management/PhabricatorRepositoryManagementUpdateWorkflow.php:59]
phacility#6 PhabricatorRepositoryManagementUpdateWorkflow::execute(PhutilArgumentParser) called at [<phutil>/src/parser/argument/PhutilArgumentParser.php:441]
phacility#7 PhutilArgumentParser::parseWorkflowsFull(array) called at [<phutil>/src/parser/argument/PhutilArgumentParser.php:333]
phacility#8 PhutilArgumentParser::parseWorkflows(array) called at [<phabricator>/scripts/repository/manage_repositories.php:22]
COMMAND
git ls-remote '********'
STDOUT
(empty)
STDERR
ssh: Could not resolve hostname -o: Name or service not known
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
and the repository exists.
at [<phutil>/src/future/exec/ExecFuture.php:369]
```

Test Plan:
How to reproduce:
1. add repository to Phabricator which is accessed via `ssh`
2. Use git 2.18+
3. Enable wire protocol in `/etc/gitconfig`:
```
[protocol]
    version = 2
```
4. Try refreshing repository: `phabricator/bin/repository update somecallsing`
5. Repository update fails with `ssh: Could not resolve hostname -o: Name or service not known`

after this changes - updates will succeed

Reviewers: epriestley, Pawka, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D19542

Author: Arturas Moskvinas

scripts/ssh/ssh-connect.php

@@ -27,7 +27,15 @@
       'param' => pht('port'),
       'help' => pht('Port number to connect to.'),
     ),
+    array(
+      'name' => 'options',
+      'short' => 'o',
+      'param' => pht('options'),
+      'repeat' => true,
+      'help' => pht('SSH options.'),
+    ),
   ));
+
 $unconsumed_argv = $args->getUnconsumedArgumentVector();
 
 if (function_exists('pcntl_signal')) {
@@ -113,6 +121,25 @@ function ssh_connect_signal($signo) {
   $arguments[] = $port;
 }
 
+$options = $args->getArg('options');
+$allowed_ssh_options = array('SendEnv=GIT_PROTOCOL');
+
+if (!empty($options)) {
+  foreach ($options as $option) {
+    if (array_search($option, $allowed_ssh_options) !== false) {
+      $pattern[] = '-o %s';
+      $arguments[] = $option;
+    } else {
+      throw new Exception(
+        pht(
+          'Disallowed ssh option "%s" given with "-o". '.
+          'Allowed options are: %s.',
+          $option,
+          implode(', ', $allowed_ssh_options)));
+    }
+  }
+}
+
 $pattern[] = '--';
 
 $pattern[] = '%s';