Add *arr Feed to check releases

[iwa]

• [x] support Sonarr
• [x] support Radarr
• [ ] widget styling has to be done

the goal is to add 2 new feed widgets:

1. first is a "Releasing today" widget, showing which episodes & movies are planned to be released the same day, with a checkmark showing if your *arr stack grabbed the file

2. second would be a simple "Latest grabbed releases", acting as a kind of logs to show the most recent grabbed releases by your stack

current config format

          - type: arr-stack-releases
            sonarr:
              enable: true or false // include or not sonarr in the feed
              endpoint: "url or ip"
              apikey: "apikey of sonnar"
            radarr:
              enable: true or false // include or not radarr in the feed
              endpoint: "url or ip"
              apikey: "apikey of radarr"

fixes #95

[iwa]

first one is working, still need to dig api docs for the "latest grabbed releases" widget

@svilenmarkov do you mind taking a peak at the code to be sure it's written and organized as you prefer? don't hesitate to suggest anything, specially if it's about the design (im not good with designing.......)

edit: also, i'll work on adding the docs afterwards in case you want to reorganize things