Move table routes formatter class to the inspector and rename it

It feels more consistent to have this class called "HtmlTableFormatter",
and to have it here with the routes inspector and console formatter,
since it's used for both routing error exceptions and the rails info
page.
Rename route_wrapper partial layout to table

It is used by the table formatter only, and it's already inside a routes
directory that namespaces it properly, so calling it just "table" seems
simpler.
Rescue from LoadError when trying to load the debugger gem for console

Avoid swallowing all exceptions that might happen when requiring
debugger, just catch a LoadError if it cannot be loaded.

Check for more background:
https://github.com/rails/rails/commit/28fd867c9bc790636d37a28f288791cd0089a6fd#commitcomment-2386952