VC: Add Missing Command Line Arguments

[jclapis]

I'm testing the new split VC architecture (#3798) and the VC is missing some command line arguments I use for Rocket Pool. Specifically, I'm looking for these three:

--insecure-netkey-password
--doppelganger-detection
--suggested-fee-recipient

The --network flag isn't accepted either, but if the VC pulls network info from the BN then it doesn't need to be there. I'm not sure if that's the case or not so I'll mention it here.

Additionally, these flags should be added so both the BN and the VC support them:

--metrics
--metrics-address
--metrics-port

I assume things like beacon_attestations_sent_total, beacon_blocks_proposed_total, next_action_wait, and beacon_attestation_sent_delay_bucket will come from the VC since it's in charge of attesting, while things like nbc_peers would remain in the BC? It doesn't particularly matter to me where they come from, as long as it's consistent and it works.

[arnetheduck]

beacon_attestations_sent_total

Some of these will likely be present in both VC and BN given the BN can operate some keys whiles the VC does the rest (ie the BN can still host an "internal" VC regardless if the API is used)

[arnetheduck]

See also #3683, #3680

[tersec]

#3877 adds doppelganger detection and #3915 addresses the metrics.

[zah]

The validator client does not connect to the Ethereum P2P network, so the option --insecure-netkey-password is not relevant for it. The network information is indeed pulled from the connected beacon node. #3976 adds the last missing command-line options (--suggested-fee-recipient).

Currently, the validator client supports some of the beacon node metrics, but beacon_blocks_proposed_total and next_action_wait in particular are still missing.