add "Governed By Optimism" field to the chain lists

[tessr]

In the time since we originally spec'd out the SCR, we've aligned on "Governed by Optimism" as a key criteria and differentiator for chains. We should include this field in chainList.toml and chainList.json in addition to the superchainLevel.

(Note that superchainLevel requires that chains both have their ProxyAdminOwner role set to the 2/2 and that the chain uses permissionless FPs, e.g., that the chain is on the latest gov-approved version. "Governed by Optimism" should refer only to the key handover status.)