Ability to add custom root CAs

Certain customer checks require a custom root CA to work. It would be helpful to be able to add custom root CAs, similarly to how we can add client certificates.

Currently, the only way to do this is by hosting a private location and setting up the root CA there. Another workaround (in the case of Playwright scripts) is to set ignoreHTTPSErrors: true, but this means we can’t monitor legitimate certificate issues like revocation or expiration.