Add repository URI view pages and IO/Display edit logic

Summary:
Ref T10748.

  - New View page for repository URIs.
  - Make display and I/O behavior (observe, mirror, read, read/write) editable.
  - Add a bunch of checks to prevent you from completely screwing up a repository by making it writable from a bunch of differnet sources.

Test Plan:
{F1249866}

{F1249867}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10748

Differential Revision: https://secure.phabricator.com/D15816

src/applications/diffusion/application/PhabricatorDiffusionApplication.php

@@ -91,8 +91,11 @@ final class PhabricatorDiffusionApplication extends PhabricatorApplication {
             => 'DiffusionCommitEditController',
           'manage/(?:(?P<panel>[^/]+)/)?'
             => 'DiffusionRepositoryManageController',
-          $this->getEditRoutePattern('uri/edit/')
-            => 'DiffusionRepositoryURIEditController',
+          'uri/' => array(
+            'view/(?P<id>[0-9]\d*)/' => 'DiffusionRepositoryURIViewController',
+            $this->getEditRoutePattern('edit/')
+              => 'DiffusionRepositoryURIEditController',
+          ),
           'edit/' => array(
             '' => 'DiffusionRepositoryEditMainController',
             'basic/' => 'DiffusionRepositoryEditBasicController',