Fix duplicate project roots in multi-root workspaces

[wenyt (wenytang-ms)]

Summary

• refresh the project tree when project-import events arrive after the language server is fully ready
• keep progressive project insertion limited to single-folder workspaces so multi-root trees cannot mix WorkspaceNode and ProjectNode roots
• normalize project file paths before deduplication, including Windows URI variants and trailing separators
• add single-root URI deduplication and mixed multi-root regression coverage

Multi-root workspaces now wait for the final server-ready refresh instead of showing incorrectly grouped progressive placeholders. Single-root progressive loading remains unchanged.

Testing

• npm run compile
• npm run tslint
• Maven Project View Tests: 14 passing
• Multiple Project View Tests: 1 passing

Fixes #1060
Related to redhat-developer/vscode-java#4478

UI verification

Before (#4478): the Java project genAicmaa is incorrectly nested under the non-Java SagApkGen workspace folder.

After: workspace-folder ownership is preserved: my-app is under maven, while non-java remains an empty workspace root.

The visibility of an empty non-Java workspace root is separate behavior tracked by #758.

[Copilot]

Pull request overview

Fixes duplicate or misplaced Java project roots in multi-root workspaces, addressing #1060 and related issue #4478.

Changes:

• Restricts progressive insertion to single-root workspaces and normalizes URI deduplication.
• Refreshes normally for post-readiness import events.
• Adds integration and AutoTest regression coverage.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.github/workflows/e2eUI.yml	Uses Node.js 22 for AutoTest jobs.
src/languageServerApi/languageServerApiManager.ts	Refreshes after ready-state imports.
src/views/dependencyDataProvider.ts	Guards progressive insertion and normalizes URIs.
test/e2e-plans/java-dep-project-explorer.yaml	Adds mixed multi-root UI coverage.
test/index.ts	Runs the new multi-root suite.
test/maven-suite/projectView.test.ts	Tests equivalent-URI deduplication.
test/multiple-suite/index.ts	Configures the multi-root test runner.
test/multiple-suite/projectView.test.ts	Tests multi-root node structure.
test/multiple/multiple-project.code-workspace	Adds a non-Java workspace root.
test/non-java/package.json	Provides the non-Java fixture.

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