[Backport to 3.2.x][Fixes #8524] Missing "anonymous group" permissions within GeoFence r…

[afabiani]

…ules

Checklist

Reviewing is a process done by project maintainers, mostly on a volunteer basis. We try to keep the overhead as small as possible and appreciate if you help us to do so by completing the following items. Feel free to ask in a comment if you have troubles with any of them.

For all pull requests:

• Confirm you have read the contribution guidelines
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• Make sure the first PR targets the master branch, eventual backports will be managed later. This can be ignored if the PR is fixing an issue that only happens in a specific branch, but not in newer ones.

The following are required only for core and extension modules (they are welcomed, but not required, for contrib modules):

• There is a ticket in https://github.com/GeoNode/geonode/issues describing the issue/improvement/feature (a notable exemption is, changes not visible to end-users)
• The issue connected to the PR must have Labels and Milestone assigned
• PR for bug fixes and small new features are presented as a single commit
• Commit message must be in the form "[Fixes #<issue_number>] Title of the Issue"
• New unit tests have been added covering the changes, unless there is an explanation on why the tests are not necessary/implemented
• This PR passes all existing unit tests (test results will be reported by travis-ci after opening this PR)
• This PR passes the QA checks: flake8 geonode
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Submitting the PR does not require you to check all items, but by the time it gets merged, they should be either satisfied or inapplicable.

[codecov]

Codecov Report

Merging #8526 (0f51bc4) into 3.2.x (7fc91ea) will increase coverage by 0.00%.
The diff coverage is 90.90%.

@@           Coverage Diff           @@
##            3.2.x    #8526   +/-   ##
=======================================
  Coverage   56.23%   56.24%           
=======================================
  Files         592      592           
  Lines       43204    43207    +3     
  Branches     5642     5642           
=======================================
+ Hits        24297    24302    +5     
+ Misses      17449    17448    -1     
+ Partials     1458     1457    -1