fix(amazonq): edit diff UI doesnt render correctly when the diff contains only space char or empty line

[Will-ShaoHua]

Problem

The suggestion indicates the empty line (L4) is edited and replaced with suggestion content however there is no diff highlight. Reason behind is because the function diffWordsWithSpace will not say the line is removed (since it's be edited). https://github.com/aws/aws-toolkit-vscode/blob/master/packages/amazonq/src/app/inline/EditRendering/svgGenerator.ts#L437-L441

Solution

---

• Treat all work as PUBLIC. Private feature/x branches will not be squash-merged at release time.
• Your code changes must meet the guidelines in CONTRIBUTING.md.
• License: I confirm that my contribution is made under the terms of the Apache 2.0 license.

[amazon-inspector-ohio]

⏳ I'm reviewing this pull request for security vulnerabilities and code quality issues. I'll provide an update when I'm done

[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.
• This pull request implements a feat or fix, so it must include a changelog entry (unless the fix is for an unreleased feature). Review the changelog guidelines.
  • Note: beta or "experiment" features that have active users should announce fixes in the changelog.
  • If this is not a feature or fix, use an appropriate type from the title guidelines. For example, telemetry-only changes should use the telemetry type.

[amazon-inspector-ohio]

✅ I finished the code review, and didn't find any security or code quality issues.

[atonaamz]

why do we choose this number? This means 4 spaces are highlighted?

[Will-ShaoHua]

since we can only do a static rendering afaik, and the number 4 is alignment with product