Multi-select adoption for compressed tree

[benibenj]

Copilot Generated Description: Implement multi-select functionality in the compressed tree structure, allowing users to select multiple items simultaneously. This includes updates to the identity provider to support group IDs and modifications to the tree's options to preserve selection behavior.

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@joaomoreno

Matched files:

• src/vs/base/browser/ui/tree/asyncDataTree.ts
• src/vs/base/browser/ui/tree/compressedObjectTreeModel.ts

[Copilot]

Pull request overview

Adds support for grouped selection (via IIdentityProvider.getGroupId) when using compressed tree nodes, ensuring multi-select behavior continues to work when identity providers are wrapped/mapped through tree layers.

Changes:

• Propagate getGroupId through compressed tree identity-provider wrappers (wrapIdentityProvider, mapOptions).
• Propagate getGroupId through AsyncDataTree’s diffIdentityProvider wrapper.
• Add regression tests around updateOptions() preserving wrapped identity/accessibility providers.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/vs/base/test/browser/ui/tree/objectTree.test.ts	Adds tests and helpers to validate wrapped providers survive updateOptions() and still drive selection/type-nav behavior.
src/vs/base/browser/ui/tree/compressedObjectTreeModel.ts	Extends compressed-tree identity provider wrapping to forward getGroupId to underlying elements.
src/vs/base/browser/ui/tree/asyncDataTree.ts	Extends diffIdentityProvider wrapper to forward getGroupId for nodes.