Rename Id-property for parameterized items

[fflaten]

Should we just rename the Id-property to GroupId and use a guid to make it more obvious? It's a public property, but I doubt anyone relies on it and the fact that it's startline atm.

Originally posted by @fflaten in https://github.com/pester/Pester/pull/2208#discussion_r1145464399

Keep Id-property as obsolete until next major release.