Prevent entry owner viewing PDF if Restrict Owner setting enabled

[jakejackson1]

Description

Update middleware to correctly show an error if the entry owner tries viewing a PDF with the Restrict owner setting enabled and they don't have appropriate capabilities.

Testing instructions

1. Create PDF on form and turn on Restrict Owner security setting
2. Create new subscriber user on site
3. Login as subscriber
4. Submit Gravity Form
5. Try view PDF as subscriber (access denied)
6. Turn off Restrict Owner security setting
7. Try view PDF as subscriber again (can see PDF)
8. Logout
9. Submit form as logged out user
10. Try view PDF as logged out user (access denied)
11. Login as administrator
12. Try view first and second PDFs (can see PDFs)
13. Submit form as administrator
14. Try view PDF (can see PDF)

Checklist:

• I've tested the code.
• My code is easy to read, follow, and understand
• My code follows the accessibility standards.
• My code has proper inline documentation / docblocks.

Additional Comments

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.83%. Comparing base (141c78b) to head (94f586a).
Report is 1 commits behind head on development.

Additional details and impacted files

@@             Coverage Diff              @@
##           development    #1567   +/-   ##
============================================
  Coverage        77.83%   77.83%           
============================================
  Files              252      252           
  Lines            13920    13921    +1     
  Branches           370      370           
============================================
+ Hits             10834    10835    +1     
  Misses            3078     3078           
  Partials             8        8           

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[jakejackson1]

@todo - add new unit tests that run all actions on the middleware filter and verify the outcome is what is expected.