[docs] Create a unified CI guide

[titerman]

What is your Scenario?

CI-specific guides are good but aren't universally applicable + it's hard to keep them up to date. Better to describe general principles

https://testcafe.io/documentation/402634/guides#continuous-integration

What are you suggesting?

Create a unified CI guide + find a way to preserve the rest of the info

What alternatives have you considered?

No response

Additional context

No response

[titerman]

See also: https://github.com/DevExpress/testcafe/issues/3270, https://github.com/DevExpress/testcafe/issues/4250