Productize segmentation

[qizhou]

Issues to address:

1. Slice with the exact no. of eid's
2. Segment sid continuation (instead of resetting to 0)
3. Better code organization (move callback to tracer?)

Tests to add:

1. Compare with continuation slice code (WIP)

[qizhou]

Latest code: https://github.com/ethstorage/zkWasm/tree/cont_es