perf(rollup): use NSplit API from sroar to improve rollup performance

[NamanJain8]

This PR improves the performance of the rollups. Also, it fixes memory issues of the bulk loader.

• Use the optimized Split API from the sroar to split the bitmap (while doing rollup). This is an improvement over the recursive binary split that was very slow.
• In bulk loader, use HandoverSkipList API instead of WriteBatch to avoid the memory constraints of doing a huge batch write.

Also, it introduces BitForbidPosting that limits the capability to store large posting lists that generate splits of length greater than the --limit max-splits flag. Once a posting list is marked as Forbidden it cannot be recovered.

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This change is 

[aman-bansal]

In alpha max splits default value is probably missing. Secondly can we make default value of max-splits equal to nquad-limits. So that it wont affect currently running workflows for customers. They can set this variable to enhance the performance