Improve: qdt files reliability

[Guts]

This PR improve qdt-files.json (HTTP handler) parsing reliability handling cases where qdt-files.json generated with tree without the --prune option and containing empty folders makes crash the reader.

2024-05-29 09:50:42||ERROR||bouncer||exit_cli_error||43||'NoneType' object is not iterable
Traceback (most recent call last):
  File "qgis_deployment_toolbelt/commands/deployment.py", line 205, in run
  File "qgis_deployment_toolbelt/jobs/job_profiles_downloader.py", line 130, in run
  File "qgis_deployment_toolbelt/profiles/remote_http_handler.py", line 120, in download
  File "qgis_deployment_toolbelt/profiles/remote_http_handler.py", line 158, in tree_to_download_list
  File "qgis_deployment_toolbelt/profiles/remote_http_handler.py", line 158, in tree_to_download_list
  File "qgis_deployment_toolbelt/profiles/remote_http_handler.py", line 150, in tree_to_download_list
TypeError: 'NoneType' object is not iterable
2024-05-29 09:50:42||ERROR||bouncer||exit_cli_error||44||Please, read the full detailed log: /home/florian.bocquet/.cache/qgis-deployment-toolbelt/logs/QGISDeploymentToolbelt_0.34.2.log
'NoneType' object is not iterable

Spotted by @Niarolf

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 95.83333% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 66.73%. Comparing base (e456316) to head (00faae8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #514      +/-   ##
==========================================
- Coverage   70.69%   66.73%   -3.97%     
==========================================
  Files          48       49       +1     
  Lines        3078     3084       +6     
  Branches      662      664       +2     
==========================================
- Hits         2176     2058     -118     
- Misses        711      831     +120     
- Partials      191      195       +4     

Flag	Coverage Δ
unittests	66.53% <95.83%> (-3.55%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...gis_deployment_toolbelt/utils/tree_files_reader.py	100.00% <100.00%> (ø)
...eployment_toolbelt/profiles/remote_http_handler.py	34.00% <50.00%> (+0.66%)	⬆️

... and 7 files with indirect coverage changes

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud