Introduce `-DInternal.DebugWorkerDelay=120` and sleep inside `RunWorker()`.
Rationale: With 2.11 we've introduced a real umbrella process where the
main process is spawned as child fork. Running icinga2 in foreground on
a macOS shell with LLDB will now exit, and not follow the child process.
LLDB doesn't support `follow-fork-mode child` like GDB and therefore we
need to:
- Print the child process PID
- Sleep for X seconds to allow the developer to run `lldb -p <PID>`, set breakpoints, etc.
This commit also documents all available debug build enabled internal constants.
5812dae55b