Changes Provider and Direct Comparison functionality

[diegopinate]

This PR aims to enhance changed elements react for:

Frontend Enhancements:

1. Provide consumers a way to inject their own changes and skip using the changed elements service altogether
2. Provide colorization overrides for any special customization logic
3. Provide a callback when changed instances are selected in the UI

Backend Enhancements:

1. Initial ChangesRpcInterface and ChangesRpcImpl which aim to allow using the Partial EC Change Unifier in a simplified way
2. The Rpc interface allows the app to provide relationships that they care about and marks any related changed ec instance with what relationships were affected that may drive the element for changes

Test App Changes:

1. The ChangesRpcInterface is used to supply changes to provide an example of usage for an app that may want specific relationships to be highlighted
2. Showcases how they could colorize changed instances based on the relationships that have changes

The Rpc is being implemented temporarily as part of the test-app-backend, but we will aim to move it to a separate package (potentially imodel-sync) to be consumable by other applications.

[Copilot]

Pull Request Overview

Adds a “direct comparison” workflow to both the test app and the changed-elements-react library by wiring in a new changes‐provider RPC path, custom styling overrides, and a selection callback.

• Introduce useDirectComparison flag and register ChangesRpcInterface/ChangesRpcImpl on frontend and backend
• Extend VersionCompare options to accept changesProvider, colorOverrideProvider, and onInstancesSelected
• Update widgets and visualization handlers to highlight driven elements and invoke custom callbacks

Reviewed Changes

Copilot reviewed 33 out of 34 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/test-app-frontend/src/environment.ts	Add useDirectComparison flag from environment variables
packages/test-app-frontend/src/App/ITwinJsApp/ITwinJsApp.tsx	Register ChangesRpcInterface, pass custom providers into VersionCompare.initialize
packages/test-app-backend/src/RPC/ChangesRpcInterface.ts	Define new RPC interface for fetching changed instances
packages/test-app-backend/src/RPC/ChangesRpcImpl.ts	Implement the RPC using ChangedInstancesProcessor
packages/changed-elements-react/src/api/VersionCompare.ts	Expand VersionCompareOptions to include changesProvider, colorOverrideProvider, and onInstancesSelected
packages/changed-elements-react/src/widgets/EnhancedElementsInspector.tsx	Invoke onInstancesSelected and inject driven-element highlighting

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

[CalebGerman]

Looks like the lock file is not correct

[diegopinate]

Looks like the lock file is not correct

Yes, I resolved that as well, had to update the pnpm version in the pipeline and fix some of the linting.

See:

• Add approved builds, fix build
• Update node and pnpm in workflows
• Fix linter and linting problems. Add interfaces for comparison metadata.