Proper Newznab Category / Download Category Support

[rix1337]

Allow creating download categories in the web UI (#299)

• Integrated /categories into main menu
• this is backward compatible, if you don't set categories in your *arr Download settings, the previous ones will be used
• default categories cannot be deleted, but modified
• set custom emojis as category icons for Quasarrs web ui
• limited to 10 custom categories. Default ones can't be deleted.

Allow setting mirror whitelist per download category

• Users can optionally set a mirror whitelist per category
• Download functions will check and use this whitelist during download

Move to numeric newznab categories for search instead of deriving search type from User Agent

• This fixes Prowlarr support #286 / Populierung über Prowlarr #155
• Prowlarr users need to query by IMDb ID to get results {ImdbId:tt0120737}
• Expose the search categories in Web UI

Allow setting hostname whitelist per search category

• Users can optionally set a mirror whitelist per category
• Download functions will check and use this whitelist during download

SponsorsHelper improvements

• New recommendation: 2Captcha support for SponsorsHelper
• Add APIKEY_2CAPTCHA to the configuration table
• Add notes on 2Captcha recommendation and fallback behavior
• Fix capitalization of API key in documentation
• For your convenience the XX_USER, XX_PASS and XX_HOSTER params were all removed
• Instead, SponsorsHelper grabs this information directly from Quasarr via the sponsors API

CAPTCHA userscripts improvement

• Automatically sign in for Junkies links that require active sessions for link retrieval.

Replace CLI arguments with environment variables

• Remove HOSTNAMES startup import logic
• Remove DEBUG env var in favor of LOG levels
• Update documentation and default configuration

Remove mirror filtering from all searches

• This is a major alignment with this projects core philosophy of simplicity
• The previous logic allowing the addition of one mirror name to the api url was error prone and created horrible code throughout the search logic
• Mirror filtering is now done solely during downloads, based on a given download categories mirror whitelist.

In other news: Major refactor of how constants are set and utils.py is used. Shared is now solely responsible for sharing state between multiple processes. All helper functions are moved to utils.