Uses some ES6 syntax. Also removes inputHeight key for resolution as it makes no sence to have dictionary with one key. Removes some code duplication. Makes code consistent: method params for updateLocalStats and updateRemoteStats.

Enable ESLint on jitsi-meet with the same configuration and the same
goals as in lib-jitsi-meet.

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.

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.

It is confusing when the name of the main class exported from the file
is not the same as the filename.

VideoContainer is a separate being which implements the LargeContainer
and it's confusing to have it in the same file. This was encouraging to
access private parts of the VideoContainer directly(not through
the interface).

When link is missing disable clicking.