When user reconnected and the avatar is displayed we need to perform
full large video update in order to transition correctly.

Renames 'videoConnectionMessage' to 'localConnectionMessage', because
it is displayed when we're having problems with our local connection
and a different one will be shown for the remote connectivity issues.

Grey filter will be applied to the remote video/avatar displayed on
"large" and a message indicating remote connectivity issues will be
shown on top of that.

The 'wasVideoRendered' flag will tell whether or not we have any video
image rendered(even if stalled) on the large video element.

When the user is having connectivity issues we use the image cached in
the video element to show the preview in greyscale. It looks like this
cached image gets invalided after prolonged periods of time the video
element being hidden(and it is hidden when the video is muted). So we
never show this image if the user gets muted during connectivity
disruption in order to avoid blackness.

We used to rely on 'currentTime' of the video element, but we execute
'updateView' from the 'onplay' callback and on fast machines it may
happen that the value is 0 even though the video has just started.

At any point of time we display one of the three: video, avatar or
blackness. The purpose of this commit is to make that fact more clear
in the code.

The video or the avatar on a thumbnail will be displayed in greyscale
when the user is having connectivity issues.

Call the callback even when clicking outside the dialog, or escaping to close it.

Moves handling of thank you dialog out of the Promise that handles the feedback and just before we redirect to welcome page.

The message about having connectivity issues should be displayed only
on top of the video like the "video problems filter" is.

Only the VideoContainer is interested in showing the video problems
filter which is meant to be displayed when ICE is disconnected.

Includes showing 1 when user is alone in the room.