test: rearrange inspector headers into convention

Test guide describes a conventional layout for test headers, review
inspector tests and reorganize to follow the convention.

PR-URL: https://github.com/nodejs/node/pull/13428


Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>