telemetry(auth): Enable load telemetry for Toolkit login webview

[keenwilson]

Problem

The Toolkit login webview throws an error when calling setUiReady() because loadMetadata is undefined:

[error] webviewId="aws.toolkit.AmazonCommonAuth": Error: Webview error
-> Error: Webview backend command failed: "setUiReady()"
-> TypeError: Cannot read properties of undefined (reading 'start')

This occurs because supportsLoadTelemetry defaults to false in the base VueWebview class, preventing the initialization of loadMetadata during webview setup. Without loadMetadata, the webview cannot track load timing or emit load telemetry.

Solution

Added one line to enable load telemetry in ToolkitLoginWebview.

This flag was originally introduced in e7b7307 to track Amazon Q webview load times and failures. We're now extending this functionality to the Toolkit login webview for consistent telemetry across both implementations.

Before fix:

Toolkit login webview error showing loadMetadata undefined. This occurs because supportsLoadTelemetry defaults to false in the base VueWebview class, preventing the initialization of loadMetadata during webview setup. Without loadMetadata, the webview cannot track load timing or emit load telemetry. The error happens here when trying to calculate duration:

const duration = globals.clock.Date.now() - this.loadMetadata!.start

After fix:

Toolkit login webview successfully loading with duration metrics.

---

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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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  • 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.

[laileni-aws]

/retryBuilds