fix(sagemaker): singleton window bug

[aws-ajangg]

Problem

• When user connects to space, it creates a duplicate window for the same space

Solution

• Assign unique identifier to workspace. This will open same external window when connecting to same workspace.

---

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[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.
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[amazon-inspector-ohio]

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

[aws-asolidu]

why can't this be session?

[aws-ajangg]

hostname also uses session but session is randomly generated in the presigned url and this is what's causing a new external window to be opened when the user tries to connect to the workspace.

After discussing with @edwardps, we decided to use a deterministic unique identifier for the hostname instead

[edwardps]

${workspaceName}_${namespace}

Please check the naming convention(limits) to confirm the characters allow by k8s can be accepted as ssh hostname.

[aws-ajangg]

Added k8s naming convention validation