fix(stepfunctions): Add document URI check for save telemetry

[l0minous]

Problem

Save telemetry was being recorded for all document saves in VS Code, not just for the active workflow studio document.

Solution

Add URI comparison check to ensure telemetry is only recorded when the saved document matches the current workflow studio document.

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[github-actions]

• This pull request modifies code in src/* but no tests were added/updated.
  • Confirm whether tests should be added or ensure the PR description explains why tests are not required.