Add unconditional logging to debugserver for launch/attach processes

Add unconditional logging to debugserver for launch/attach processes

Debugging app launch/attach failures can be difficult because of
all of the messages logged to the console on a darwin system;
emitting specific messages around critical API calls can make it
easier to narrow the search for the console messages related to
the failure.

<rdar://problem/67220442>

Differential revision: https://reviews.llvm.org/D94357