errors: trace unhandled promise rejection location

[legendecas]

Print where an unhandled promise is been rejected with flag
--trace-uncaught. This also locates the rejection site when a promise
is rejected with a primitive values.

For example, when an error is constructed at a place that's different
from where it is thrown, --trace-uncaught would print the location
where it is thrown.

const err = new Error("foo");
//          ^ this is where the error is constructed


function foo() {
  throw err;
  ^
//this is where the error is thrown
}

[legendecas]

There are a few cases where V8 calls PromiseRejectCallback not at where the promise is rejected. Might need to fix in V8 first.