[ie/niconicochannelplus] Add extractors (#5686)

Closes #2537
Authored by: pzhlkj6612

README.md

@@ -1845,6 +1845,9 @@ The following extractors use this feature:
 * `vcodec`: vcodec to ignore - one or more of `h264`, `h265`, `dvh265`
 * `dr`: dynamic range to ignore - one or more of `sdr`, `hdr10`, `dv`
 
+#### niconicochannelplus
+* `max_comments`: Maximum number of comments to extract - default is `120`
+
 #### tiktok
 * `api_hostname`: Hostname to use for mobile API requests, e.g. `api-h2.tiktokv.com`
 * `app_version`: App version to call mobile APIs with - should be set along with `manifest_app_version`, e.g. `20.2.1`

yt_dlp/extractor/_extractors.py

@@ -1299,6 +1299,11 @@
     NineCNineMediaIE,
     CPTwentyFourIE,
 )
+from .niconicochannelplus import (
+    NiconicoChannelPlusIE,
+    NiconicoChannelPlusChannelVideosIE,
+    NiconicoChannelPlusChannelLivesIE,
+)
 from .ninegag import NineGagIE
 from .ninenow import NineNowIE
 from .nintendo import NintendoIE