Make KV file read/write ops exclusive to avoid races between ops on the same disk

[govint]

This issue is for investigation at this point and changes will be made if proven. With the ability to handle multiple ops via threads we may be seeing issues where the KV is being updated by one thread and another thread read the same or accessing before even the KV is initialized. For now we don't have such cases happening, this issue is to run tests and verify if that can happen and ensure exclusive access to the KV.

[govint]

Looks like @brunotm is getting a PR with changes to support exclusive access to KV ops, closing this issue.