[FEAT] Lock for writes when validating partition

[CodeLieutenant]

For 'strong consistency' testing, during validation of partitions we should not modify the partitions, we need to introduce some kind of locking to the partitions when they are used inside selects, so that results coming from the query are the same (or at least we hope they will be) while keeping this lock

[soyacz]

This might not be only thing to modify for 'strong consistency' feature.

[dani-tweig]

Closing this issue as it was moved to Jira. Please continue the thread in https://scylladb.atlassian.net/browse/QATOOLS-112