Option is added to video_chat_provider settings for disabling
video calls.
Video call icon is hidden in two cases-
1. video_chat_provider is set to disabled.
2. video_chat_provider is set to Jitsi and settings.JITSI_SERVER_URL
is none.
Relevant tests are added and modified.
Fixes#14483
While we could fix this issue by changing the markdown processor,
doing so is not a robust solution, because even a momentary bug in the
markdown processor could allow cached messages that do not follow our
security policy.
This change ensures that even if our markdown processor has bugs that
result in rendered content that does not properly follow our policy of
using rel="noopener noreferrer" on links, we'll still do something
reasonable.
Co-authored-by: Tim Abbott <tabbott@zulipchat.com>
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>