Log cause when calling trackException

Nobody has claimed this yet.

**Is your feature request related to a problem? Please describe.**
When using `trackException` it looks like it's not propagating the [cause](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/cause) of the error. This would be really helpful so we're not loosing the context of the error.

**Describe the solution you'd like**
Log the cause if present? Not sure how the stack should be handled.

**Describe alternatives you've considered**
Manually adding the cause as custom property, but that needs to handled in all places where an exception is tracked.

**Additional context**
- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/cause

Start by locating the trackException entry point in the ApplicationInsights-JS codebase and inspect how Error data is currently collected. Use the linked MDN reference to understand Error.cause, then determine how its presence should appear in tracked exception data and how the stack should be handled; done means the cause is logged without requiring callers to add a custom property.

Written by the indexing model from the issue text.