[Fixes #12815] Add custom login view/template to support recaptcha on Login Form (#12825)

[cmotadev]

Fixes this Issue: Add Recaptcha Form on GeoNode Login
Originally put on 4.4.x branch, and now submitted to maste branch

[cla-bot]

Thank you for your pull request and welcome to our community. We require contributors to sign our Contributor License Agreement, and we don't seem to have the users @cmotadev on file. In order for us to review and merge your code, please contact the project maintainers to get yourself added.

[codecov]

Codecov Report

Attention: Patch coverage is 21.05263% with 15 lines in your changes missing coverage. Please review.

Project coverage is 67.93%. Comparing base (1c40f06) to head (6af3cac).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #12831      +/-   ##
==========================================
- Coverage   67.95%   67.93%   -0.02%     
==========================================
  Files         975      976       +1     
  Lines       58886    58895       +9     
  Branches     6886     6886              
==========================================
- Hits        40017    40012       -5     
- Misses      17232    17246      +14     
  Partials     1637     1637              

[mattiagiupponi]

Looks good and is working, but can you please run black and flake8 using the master branch versions?
You can install them via pip install --upgrade $(grep 'flake8\|black' requirements.txt)
and then running black geonode && flake8 geonode