Idea: keep ActionHistory (as audit log)

[tennox]

Describe the problem to be solved

I'm coming from this issue https://community.getgrist.com/t/find-out-who-changed-a-cell-value/7119
I found that there currently is no way to find out who changed what when in a non-superficial way.

Describe the solution you would like

From what I could gather analyzing the _gristsys_ActionHistory table - via this script - it seems an easy first step to add a setting in grist to disable pruning of that table 🤔