Refactorize RSS subcmd and related model

[Guts]

No description provided.

[codecov]

Codecov Report

Merging #99 (41630b9) into main (88dcde2) will decrease coverage by 0.08%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #99      +/-   ##
==========================================
- Coverage   65.02%   64.95%   -0.08%     
==========================================
  Files          28       29       +1     
  Lines        1281     1284       +3     
  Branches      231      231              
==========================================
+ Hits          833      834       +1     
- Misses        400      401       +1     
- Partials       48       49       +1     

Impacted Files	Coverage Δ
geotribu_cli/constants.py	100.00% <ø> (ø)
geotribu_cli/rss/mdl_rss.py	100.00% <100.00%> (ø)
geotribu_cli/rss/rss_reader.py	75.60% <100.00%> (ø)
geotribu_cli/subcommands/__init__.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes