Provide a strategy to prevent problems with test running on Linux without graphics subsystem

[miherlosev]

Then somebody runs the tests on Linux without any graphic subsystem (CI machines, docker, etc.), it gets an unclear message about browser disconnection.

The cause of the problem - it's impossible to run the browser in non-headless mode on Linux with a graphics subsystem.

We can fix it using many ways:

• inform a customer about its situation
• automatically start xvfb if it's necessary
• switch to headless mode
• etc.

We need to discuss it and choose the best approach.

[miherlosev]

#4138

[miherlosev]

After discussion with team, we decided to extend 'Cannot establish connection..' message with the phrase You run <browser_name> browser with graphic interface in Linux without graphic subsystem. Try to run <browser_name> in headless mode. For more information see https://devexpress.github.io/testcafe/documentation/guides/concepts/browsers.html#test-in-headless-mode.