hpcrun: add --dryrun option

hpcrun: add --dryrun option

Don't exec an executable; instead, output an env command that would have the same effect as the hpcrun command.

To Demonstrate

% hpcrun --dryrun /bin/ls foo bar
env \
  LD_AUDIT=/home/johnmc/hpctoolkit/hpctoolkit-build/src/tool/hpcrun/libhpcrun_audit.so \
  LD_PRELOAD=/home/johnmc/hpctoolkit/hpctoolkit-build/src/tool/hpcrun/libhpcrun.so \
  HPCRUN_AUDIT_MAIN_LIB=/home/johnmc/hpctoolkit/hpctoolkit-build/src/tool/hpcrun/libhpcrun.so \
  HPCRUN_FNBOUNDS_CMD=/home/johnmc/hpctoolkit/hpctoolkit-build/src/tool/hpcfnbounds/hpcfnbounds \
  HPCRUN_AUDIT_FAKE_AUDITOR= \
  DARSHAN_DISABLE=1 \
  HPCRUN_CONTROL_KNOBS= \
  HPCRUN_DEBUG_FLAGS= \
  HPCRUN_EVENT_LIST=CPUTIME@5000 \
  UCX_ERROR_SIGNALS=ILL,FPE,BUS \
  MONITOR_NO_SYSTEM_OVERRIDE=1 \
  /bin/ls foo bar

Backward Compatibility

• This MR does not alter the data formats.

• This MR adds a "--dryrun" option to hpcrun

Checklist

• I have run pre-commit run -a on my local checkout and fixed any reported issues.
• I have confirmed that existing tests and/or the tests added by this MR cover the changes introduced by this MR.
• I have confirmed that any added tests will be automatically run in CI.
• I have updated all relevant documentation:
  • The --help text for the tools
  • The man page for the tools
  • The change will be added to the user manual when the new user manual appears in the repository as MarkDown