Feature request - invocation by argument list instead of shell command

With an alternate syntax going through the shell could be avoided for the bench'ed command. The pre-split argument list could be embedded in the bench invocation's argument list. Two possible styles:
- bench foo -exec cmd arg1 ... \; bar baz
- bench foo bar baz -- cmd arg1 ...

No files or tests are named in the issue. Start by tracing the command-line argument parsing and bench invocation entry points; determine how either proposed syntax can pass a pre-split command without invoking a shell, and consider the supported syntax complete when the command and its arguments are executed correctly.

Written by the indexing model from the issue text.