feat: IntelliSense for entity types and attributes

[hakanson]

Description of changes

• Update to Cedar 2.4.3
• IntelliSense for entity types and attributes
  • replaced snippets.json with completion item provider
  • additional test coverage for completion item provider
• Hover help supports properties and documentation links
• Support files outside of workspace folder
• "Go to Definition" updates and fixes

Issue #, if available

#8

Checklist for requesting a review

The change in this PR is (choose one, and delete the other options):

• A backwards-compatible change requiring a minor version bump to vscode-cedar.

I confirm that this PR (choose one, and delete the other options):

• Updates the CHANGELOG with a description of my change (required for version bumps).

Disclaimer

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