Removed role 'name' field from database

The 'name' field was really redundant and caused confusion in the
codebase, since the 'Display' name is often used and we have a
'system_name' for the admin and public role.

This fixes #2032, Where external auth group matching has confusing
behaviour as matching was done against the display_name, if no
external_auth field is set, but only roles with a match 'name' field
would be considered.

This also fixes and error where the role users migration, on role
delete, would not actually fire due to mis-matching http body keys.
Looks like this has been an issue from the start. Added some testing to
cover. Fixes #2211.

Also converted phpdoc to typehints in many areas of the reviewed code
during the above.

tests/Auth/AuthTest.php

@@ -213,13 +213,14 @@ class AuthTest extends BrowserKitTest
     public function test_user_creation()
     {
         $user = factory(User::class)->make();
+        $adminRole = Role::getRole('admin');
 
         $this->asAdmin()
             ->visit('/settings/users')
             ->click('Add New User')
             ->type($user->name, '#name')
             ->type($user->email, '#email')
-            ->check('roles[admin]')
+            ->check("roles[{$adminRole->id}]")
             ->type($user->password, '#password')
             ->type($user->password, '#password-confirm')
             ->press('Save')