Column API to return data hash

This could be useful in verifying the sheet data, and also can be used for caching API row lookup.

Right now the column API returns items->field, items->dataType, etc… Along with that, if it could compute and return another items->dataHash, with a hash value (say sha512) of all cellData in that column.

For example, in a sheet like this,

A B C

1 abc def ghi
2 jkl mno pqr

items->dataHash could return {items: [{“field” : “A”, … “dataHash”: hash(‘sha512’, A1.A2) },…]} which would be hash of concatenated string “abcjkl”.