Dependent file upload fails when confirm revision is detected

[NateWr]

Describe the bug
When uploading a dependent file that has a name similar to an existing file, the software will detect a possible duplicate and ask the user if this is a revision of an existing file.

If you select no, it is not a dependent file, and click next, the upload fails with an exception in the authorization handler.

I was only able to reproduce this with dependent files.

I suspect this is related to authorization changes made in #6257. If so, it may not effect the master branch.

To Reproduce
Steps to reproduce the behavior:

1. Go to any submission.
2. Upload a .html file.
3. In the dependent files area, upload an image file.
4. In the same dependent files area, upload the image file again.
5. See the possible revision warning and select "This is not a revision of an existing file"
6. See that the upload fails.

What application are you using?
OJS 3.2.1-2

Additional information
The error log:

[04-Dec-2020 12:18:20 Europe/London] PHP Fatal error:  Uncaught Error: Call to a member function getAuthorizationMessages() on null in /home/nate/Projects/pkp/ojs-stable/lib/pkp/classes/handler/PKPHandler.inc.php:171
Stack trace:
#0 /home/nate/Projects/pkp/ojs-stable/lib/pkp/classes/core/PKPRouter.inc.php(395): PKPHandler->getLastAuthorizationMessage()
#1 /home/nate/Projects/pkp/ojs-stable/lib/pkp/classes/core/PKPComponentRouter.inc.php(257): PKPRouter->_authorizeInitializeAndCallRequest(Array, Object(Request), Array)
#2 /home/nate/Projects/pkp/ojs-stable/lib/pkp/classes/core/Dispatcher.inc.php(143): PKPComponentRouter->route(Object(Request))
#3 /home/nate/Projects/pkp/ojs-stable/lib/pkp/classes/core/PKPApplication.inc.php(281): Dispatcher->dispatch(Object(Request))
#4 /home/nate/Projects/pkp/ojs-stable/index.php(68): PKPApplication->execute()
#5 {main}
  thrown in /home/nate/Projects/pkp/ojs-stable/lib/pkp/classes/handler/PKPHandler.inc.php on line 171

[NateWr]

This happens when a handler's authorize method returns false without adding any policies. In such cases there is no AuthorizationDecisionManager. The PRs below fix this by checking for an AuthorizationDecisionManager before trying to get the last failure message.

PRs (master):
#6534
pkp/ojs#2979

PRs (stable):
#6535
pkp/ojs#2978

[NateWr]

Ugh.. I went through all this and forgot to fix the original problem: that there is an auth failure. Working on that now...

[NateWr]

Ok, fixed the authorization problem in stable-3_2_1. It doesn't exist in the master branch because we have abandoned the revision confirmation form. I removed some dead code in master related to that.

Tests are running.

[NateWr]

Merged.