telemetry: record metric when a tree node fails to load

### Problem:

1. No metrics for when a tree node fails.
2. No metrics when user clicks to view error logs.

Note: we have `recordAwsShowExplorerErrorDetails` in `showErrorDetails.ts` but that only tracks when a user chooses to view error details.

### Proposal:

1. Create a new metric `treeNodeError` with a field for the exception name/code
2. In e.g.`treeNodeUtilities.ts:makeChildrenNodes()` record the new metric when an error occurs.
3. call `recordAwsShowExplorerErrorDetails` in `aws.viewLogsAtMessage` (see `registerLoggerCommands()`)

Start with treeNodeUtilities.ts at makeChildrenNodes() and inspect how errors are handled. Then review showErrorDetails.ts and registerLoggerCommands(), including aws.viewLogsAtMessage and recordAwsShowExplorerErrorDetails. Done means tree-node failures record treeNodeError with the exception name/code, and viewing error logs records the existing metric.

Written by the indexing model from the issue text.