[Backport to 7.9] channel manager cannot save channel settings when hst:scheme is set to https

If the attribute hst:scheme=https at hst:hosts or hst:root, then is not possible to save the channel manager changes, an error popup will show in the screen and an exception will be thrown: "Illegal channel URL scheme: https. Only 'http' is currently supported"
The error is generated from the following code.

class ChannelManagerImpl
..
private URI getChannelUri(final Channel channel) throws ChannelException {
URI uri;

try

{ uri = new URI(channel.getUrl()); }

catch (URISyntaxException e)

{ throw new ChannelException("Invalid channel URL: '" + channel.getUrl() + "'"); }

if (!"http".equals(uri.getScheme()))

{ throw new ChannelException( "Illegal channel URL scheme: '" + uri.getScheme() + "'. Only 'http' is currently supported"); }

if (StringUtils.isBlank(uri.getHost()))

{ throw new ChannelException("Channel URL '" + uri + "' does not contain a host name"); }

return uri;
}