Add validation if SC tunnel is active and add delay on start of test execution

[NatalliaSamarava]

Is your feature request related to a problem? Please describe.
Currently we have a random failes in Saucelabs tests. We are using Sauce connect , one and multithreading. The error in Saucelabs is "Misconfigured -- No active tunnel found for provided identifier".

Describe the solution you'd like
We had a call with engineer from Saucelabs and as solution to fix this error he provided to add an extra validation if Tunnel is active after the success message that we can start our test. Here is a information that he sent:
"We support multiple readiness checks. In the example I shared on the call I used the Tunnel REST API listed on this page:
https://docs.saucelabs.com/secure-connections/sauce-connect/setup-configuration/readiness-checks/
This is the actual demo: https://github.com/StuMinch/check_tunnel_status "

Describe alternatives you've considered
As an extra step it should be good to have an configurable property to set a delay start of test execution.