feature(cli): add command to export rules context in current environment

[Guts]

Following up #491.

This PR adds a new CLI command to allow export rules context in the current environment. It aims to make rules writing easier:

> qdt export-rules-context -o qdt_rules_context.json
Rules context exported in qdt_rules_context.json

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 96.66667% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 70.79%. Comparing base (c7f7608) to head (2399230).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #492      +/-   ##
==========================================
+ Coverage   70.47%   70.79%   +0.31%     
==========================================
  Files          48       48              
  Lines        3028     3054      +26     
  Branches      653      654       +1     
==========================================
+ Hits         2134     2162      +28     
+ Misses        704      702       -2     
  Partials      190      190              

Flag	Coverage Δ
unittests	70.17% <96.66%> (+0.32%)	⬆️

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

Files	Coverage Δ
qgis_deployment_toolbelt/cli.py	80.70% <100.00%> (+1.85%)	⬆️
qgis_deployment_toolbelt/profiles/rules_context.py	100.00% <ø> (ø)
..._deployment_toolbelt/commands/cmd_rules_context.py	95.83% <95.83%> (ø)

... and 1 file 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

[jmkerloch]

LGTM !