[keyserver] add script to force users to acknowledge updated policy

Summary: The script is for the case where already present policy was updated and we need to force user to acknowledge it again.

Test Plan:

1. Run yarn script dist/scripts/force-policy-acknowledgment.js
2. Check if in all policy_acknowledgments rows with given policy and confirmation date lower than the date when policy was published confirmed column was flipped to 0.

Reviewers: atul, marcin, ashoat, tomek

Reviewed By: atul, marcin, ashoat, tomek

Subscribers: ashoat, atul, abosh

Differential Revision: https://phab.comm.dev/D5310