Re-implement handling of --tlimit (#4655)

Re-implement handling of --tlimit (#4655)

As a first step within this project, this PR provides a new implementation that backs --tlimit. It uses setitimer (as timer_settime is not available on MacOS) to make the OS send a signal after the given wall clock time has passed.
In more detail, this PR:

removes the current handling of --tlimit (TlimitListener and its integration in the NodeManager)
adds a new TimeLimitListener that lives in src/main
uses TimeLimitListener directly in runCvc4()
adds a signal handler for SIGALRM (that also uses the existing timeout_handler)