[k2] Add support for multiple sync/async stack switches in backtrace algorithm

[denisichh]

General

This PR improves collecting of async stack traces in runtime-light

Problem

The current collecting backtrace doesn't handle jumps from an async stack to a sync stack and back, as only 1 async stack root is supported

Solution

Added creating of new async stack roots and added forwarding of pointers to the next async stack root