now length check is on encrypted data if encryption is on 

now specific files can be reorganized by using query

refacored index add operations

refactored code to use indexStore

1) import with updating index entries instead of replacing existing index file
2) atomic replace support for darwin platform

added feature to import/export as fdb data in zip format

1. Fix: got length of cyphertext is less than 0 error on empty file read.

1. Fix: Disable encryption for append bucket as no way to read encrypted data.

fix: exporting index files by filtering with queries 

1. Add: Lazy writer for append bucket

1. Add: Enable lazy writing for normal bucket

added feature to export and import data into fdb

Fix: Index file not created in some cases. Ex. For asset FDB on another drive.

removed unnecessary logs

1. Fix: Failed to get json data from pack on asset update.
2. Fix: Failed to get content-type from meta data.

1. Add: Hash length check to avoid runtime panic

1. Fix: Os specific row id generation.

1. FIx: Normal bucket operations