* Extract primary channel routes from invidious.cr
Also removes timedtext_video stub since all it does is redirect to the
homepage. However, Invidious's 404 handler already does this.
--
As the template for the channel about page doesn't exist yet, the
behavior for the /channel/:ucid/about endpoint has been changed to be
the same as what's currently present on Invidious
(cherry picked from commit 8fad19d8057d7d22e3de27ebbc88a9978c1df27b)
* Manually extract brand_redirect from 1b569bbc99207cae7c20aa285f42477ae361dd30
This commit manually extracts the brand_redirect function from the
commit mentioned.
However, the redirect to the `.../about` endpoint is removed due to the
fact that it doesn't exist yet.
This commit is also mainly just a bridge for the next few cherry picks from
\#2215
* Update brand_redirect to use youtubei resolve_url
(cherry picked from commit 53335fe7cfdfac392365b7cac447bc7cc6478134)
* Add additional channel endpoints to brand_redirect
(cherry picked from commit 8fc6f3add637dabb09b2034f4d82fc3d039ba15c)
* Add separate handler for /profile endpoint
* Add /channel/:ucid/home route
* Document all channel brand_urls
