tests/test-char: Check websocket chardev functionality

tests/test-char: Check websocket chardev functionality

Test order:
    Creating server websocket chardev
    Creating usual tcp chardev client
    Sending handshake message from client
    Receiving handshake reply
    Sending ping frame with "hello" payload
    Receiving pong reply
    Sending binary data "world"
    Checking the received data on server side
    Checking of closing handshake

Signed-off-by: Julia Suvorova <[email protected]>
Message-Id: <20181018223501[email protected]>
Reviewed-by: Daniel P. Berrangé <[email protected]>
Reviewed-by: Marc-André Lureau <[email protected]>
Reviewed-by: Stefan Hajnoczi <[email protected]>