New error UX

[texodus]

This PR adds a new UX for capturing the error details on hover over the error status icon. Additionally, the perspective_js::ApiError error type has been upgraded to thiserror derived version, in order to support the new UX features:

• Instances of duplicated stack trace inlining have been removed.
• String -> Rich error type -> String -> Rich error type -> ... conversions flattened to use ApiError everywhere.
• Better stacktraces (in debug builds), better error messages with categories overall.
• UI is no longer borked nor does it auto-reset (though dismissing the dialog will reset the viewer).
• Rust API has changed to take ClientError/ApiError for Client::on_error callbacks, which is an API breaking change (though this type implements Display also).