Added favorite management using Telegram

[floriegl]

Pull Request Checklist:

• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Did you make your Pull Request on the dev branch?
• Does your submission pass tests? make test
• Have you lint your code locally prior to submission? make lint
• Could you build and run the docker image successfully? make image
• Could you create a running executable? make executable
• Have you added an explanation of what your changes do and why you'd like to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran manual tests with your changes locally?

[floriegl]

This MR adds /listfavorites (to list all favorites), /listfavoriteids (to list all ids of the favorites), /addfavorites (to add item ids to favorites), /removefavorites (to remove item ids from favorites) and the possibility to change the favorite status of an item by sending the link to the bot.

[codecov]

Codecov Report

Patch coverage: 48.45% and project coverage change: -0.54% ⚠️

Comparison is base (8b6ea89) 57.85% compared to head (0030ca9) 57.32%.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #386      +/-   ##
==========================================
- Coverage   57.85%   57.32%   -0.54%     
==========================================
  Files          25       26       +1     
  Lines        1801     1891      +90     
==========================================
+ Hits         1042     1084      +42     
- Misses        759      807      +48     

Files Changed	Coverage Δ
src/scanner.py	0.00% <0.00%> (ø)
src/notifiers/telegram.py	16.37% <14.54%> (-1.50%)	⬇️
src/models/__init__.py	100.00% <100.00%> (ø)
src/models/favorites.py	100.00% <100.00%> (ø)
src/notifiers/notifiers.py	48.97% <100.00%> (ø)

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