lib: cache source maps in vm sources
Cache source maps found in sources parsed with vm.Script,
vm.compileFunction, and vm.SourceTextModule. Also, retrieve source
url from V8 parsing results.
Not like filenames returned by CallSite.getFileName() in translating
stack traces, when generating source lines prepended to exceptions,
only resource names can be used as an index to find source maps, which
can be source url magic comments instead. Source url magic comments
can be either a file path or a URL. To verify that source urls with
absolute file paths in the source lines are correctly translated,
snapshots should include the full snapshot urls rather than
neutralizing all the path strings in the stack traces.