Expose deployment block number of stake table contracts to clients

[sveitser]

See comments in InitializedAt.sol for reasons for this change.

Some more background. When querying infura or alchemy for logs there are limits, for infura its

To prevent queries from consuming too many resources, eth_getLogs requests are currently limited by three constraints:

• A maximum of 5,000 parameters in a single request
• A maximum of 10,000 results can be returned by a single query
• Query duration must not exceed 10 seconds

for alchemy its

You can make eth_getLogs requests on any block range with a cap of 10K logs in the response OR a 2K block range with no cap on logs in the response and 150MB limit on the response size

The way to limit queries is to specify a from and a to block. However, absent any other information there is no good value for the from block.

Clients can now read initializedAtBlock and start fetching events from that block.

[alxiong]

wait, shouldn't the upgradable's constructor be:

constructor() {
    _disableInitializers();
}

[sveitser]

Based on the documentation https://docs.openzeppelin.com/contracts/4.x/api/proxy#Initializable-_disableInitializers--

I think this is equivalent, because this constructor calls the initializer, and the initializer cannot be called again so the contract is never not initialized. When we inherit from this contract in other contracts the constructor of this contract is not called unless manually invoked which is just something we must not do.

Let me add a test for it.

[sveitser]

6fabe36

[alxiong]

Lgtm