debugger: rename internal module

All other files in `lib/internal` do not start with `_`. For
consistency, move `lib/internal/debugger/_inspect.js` to
`lib/internal/debugger/inspect.js`.
 Please enter the commit message for your changes. Lines starting

Author: Trott

lib/internal/debugger/_inspect.js renamed to lib/internal/debugger/inspect.js

@@ -13,5 +13,5 @@ markBootstrapComplete();
 
 // Start the debugger agent.
 process.nextTick(() => {
-  require('internal/debugger/_inspect').start();
+  require('internal/debugger/inspect').start();
 });