Make dwds serve dart objects

Currently, upon stack, scope, or object requests from IDEs, dwds does some heuristic processing of JavaScript frames and variables in current scope to make them appear as coming from dart. While that approach work in many cases due to JavaScript code produced by DDC being very close to dart, there are some corner cases where the heuristics fail. This also imposes limitations on changes in DDC, as they may break the heuristics.

We need a more reliable approach where the debugger can use compiler's symbol and type information, as well as mapping from JavaScript to dart symbol and type (via locations?) in order to have dart-oriented internal representation of stacks, scopes, and objects.

**Related issues**

https://github.com/dart-lang/sdk/issues/40776

No files, tests, or entry points are named. Start by reading the related issue 40776 and tracing how compiler symbol and type information could replace heuristic processing; done means stacks, scopes, and objects have a reliable Dart-oriented representation.

Written by the indexing model from the issue text.