Add Entry.ExpNumKeys() mthod.

Add Entries.ExpErr(), Entries.NotExpErr() and Entry.ExpErr().

Handle multi line log messages.

Add ExpError method.

Add calls to t.Helper(), add method Entry.ExpStrContains(), Entry.Map…

…(), code style edits.

Add ExpKey, NotExpKey methods.

Add ExpEntry, ExpLen methods.

Add method Logger to the Tester.

Add method Reset to the Tester, update to zerolog 1.25.

Cherry pick https://github.com/jsautret changes.