feat: Cedar 3.1.3 and human-readable schema

[hakanson]

Description of changes

• Update to Cedar 3.1.3 and other project dependencies
• Initial human-readable schema support
• IntelliSense and hover help updates
• Convert validating schema from Problem (Info) to clickable Code Lens at top of document
• Update to "Copyright Cedar Contributors"
• Various code refactoring and cleanup

Issue #, if available

• Make it possible to use the human-readable schema format #17
• Narrow suggestions in when and unless clauses #19

Checklist for requesting a review

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

• A bug fix or other functionality change requiring a patch 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

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[hakanson]

Note: leaving this PR as work in progress until Cedar 3.1.3 crates are released, then will mark as Ready for review