[display] think about how to handle _std in workspace symbols

I recently improved workspace symbols to include the package path for types (previously VSCode would fall back to using the file path since we provided no container name).

This has the downside that it leads to identical results in some cases with target specific implementations in e.g. `std/js/_std`:


Not sure how the two `ValueType` entries should best be distuingished here, should the second one have something like `Type (js)` as its "container name"?

No file or test is named. Start by tracing the workspace-symbol behavior that adds package paths for types, then compare the duplicate ValueType entries from std/js/_std. Done means target-specific implementations are distinguishable in workspace-symbol results without relying on file paths.

Written by the indexing model from the issue text.