[api/clients/v2] Determine when to yield ErrorFailover

[ethenotethan]

For EigenDA V1 client, we use a ErrorFailover type which is interpreted by the eigenda-proxy as a 503 status code - informing a secure rollup that liveness guarantees are unfulfilled by EigenDA which the rollup uses to "failover" to another DA destination (e.g, calldata, 4844 blobs, centralized S3 backend store).

Currently for V2, an ErrorFailover is only up-channeled in the disperserClient if it fails to initialize a connection or instantiate accountant state (see here).

We'll need to critically analyze the V2 payload disperser and internal disperser client to understand when an error type indicates critical liveness outage for EigenDA and return ErrorFailover accordingly in affected checks.

cc - @litt3, @samlaf