WIP: src,inspector: add --inspect-silent option

Allow the inspector to be used without printing anything to the console. This is useful when working with tools that know how to use the inspector.

If this is OK, I'll add the tests and docs.

Fixes: https://github.com/nodejs/node/issues/12665

R= @eugeneo

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)