⚡️ CamGear: Added a new YT_backend Internal Class with YT-DLP backend

[abhiTronix]

Description

This PR implements YT_backend a new CamGear's Internal YT-DLP backend class for extracting metadata from Streaming URLs.

Notable Changes:

• ✨ Implemented YT_backend a new CamGear's Internal YT-DLP backend class for extracting metadata from Streaming URLs.
• ✨ Added support for pipeling (live) video-frames from all yt-dlp supported streaming sites: https://github.com/yt-dlp/yt-dlp/blob/master/supportedsites.md#supported-sites
• ⚡️ Implemented algorithm from scratch for auto-extracting resolution specific streamable URLs for pipelineing.
• ⚡️ Implemented logic for auto-calculating best and worst resolutions.
• ✨ Added is_livestream global YT_backend parameters.
• ✨ Added default options for yt-dlp for extracting info_dict(metadata) of the video as a single JSON line.
• ✨ Added new ytv_metadata global parameter to CamGear for accessing video's metadata(such as duration, title, description) on-the-go.
• 💥 Removed automatic enforcing of GStreamer backend for YouTube-livestreams and made it optional.
• ⚰️ Completely removed old logic for extracting streams using pafy.
• ⚠️ Playlists are still unsupported.
• CamGear:
• 💥 Removed streamlink backend support from stream_mode in favor of more reliable CamGear's Internal YT-DLP backend class for extracting metadata from Streaming URLs.
• ⚰️ Removed all dead code related to streamlink backend.
• 🐛 Fixed KeyError Bug for missing attributed in meta_data json in some streaming sites.
• 💥 CamGear will raise ValueError if streaming site URL is unsupported by yt-dlp backend.
• 💥 CamGear will raise ImportError if yt-dlp isn't installed and stream_mode is enabled.
• Docs:
  • 📝 Added complete usage docs with new CamGear's Internal Class with YT-DLP backend.
  • 🚩 Updated CamGear parameters.
  • 📝 Added instructions to extract video's metadata.
  • 📝 Updated Admonitions with related information.
  • 🔥 Removed any pafy and streamlink references.
  • 💄 Updated Functional Block Diagram(gears_fbd.png) image.
  • ♿️ Updated installation instructions.
• ⚰️ Removed dead code.
• 💡 Updated code comments.
• Helper:
  • 💥 Removed restore_levelnames method.
  • 💥 Removed youtube_url_validator helper method.
• Setup.py:
  • ➖ Removed streamlink dependency.
  • ➖ Removed pafy dependency.
  • 🎨 Removed pyzmq from latest_version group.
  • 🏷️ Updated SEO Keywords.
• Maintenance:
  • 🔥 Removed unused imports.
  • 🔊 Updated logging messages.
  • 💡 Updated code comments.
• CI:
  • 💚 Restored test_stream_mode CamGear test.
  • 👷 Updated Streaming Sites link.
  • 👷 Added more tests cases.

Requirements / Checklist

• I have read the PR Guidelines.
• I have read the Documentation.
• I have updated the documentation accordingly(if required).

Related Issue

#273
#244
#133

Context

This PR is going to implement CamGear's Internal YT-DLP backend class based on yt-dlp backend for extracting metadata from YouTube API.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[codecov]

Codecov Report

Merging #274 (522aa02) into testing (cd481c1) will increase coverage by 0.56%.
The diff coverage is 93.50%.

@@             Coverage Diff             @@
##           testing     #274      +/-   ##
===========================================
+ Coverage    94.60%   95.16%   +0.56%     
===========================================
  Files           16       16              
  Lines         3040     3063      +23     
===========================================
+ Hits          2876     2915      +39     
+ Misses         164      148      -16     

Impacted Files	Coverage Δ
vidgear/gears/helper.py	93.93% <ø> (-0.13%)	⬇️
vidgear/gears/camgear.py	95.58% <93.50%> (+10.20%)	⬆️

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