strace: Print detailed signal information

- Add support for retrieving the `siginfo_t` structure of a signal
event from the Debugger API.
- Add code to `strace` to display this information every time a
signal event occurs, similar to the Linux `strace` tool.

Change-Id: If4e92bbae049ee0b52efaf9fc911d66511da62f4
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6393
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>