feat: epoch change window

[daltoncoder]

Description

Currently epoch change happens instantly when 2/3rd of the committee is ready to change. We would like this instead to trigger a 1 hour window leading up to the epoch change. In this window nodes would be able to contribute to the randomness that chooses the next committee and also aggregate the reputation scores for the day.

Checklist

• I have ensured that my version is up-to-date
• I have ensured that my issue is reproducible
• I have ensured that my issue is not a duplicate