Reorg Config Spec Modifications

[0xmrree]

Issue Addressed

Need to source REORG_HEAD_WEIGHT_THRESHOLD, REORG_PARENT_WEIGHT_THRESHOLD, REORG_MAX_EPOCHS_SINCE_FINALIZATION from config.yaml and include in spec API

Which issue # does this PR address?
#8571
This is 2/2 PR to address the above issue, the other is #8601

Proposed Changes

as advised by feedback

1. If cli props proposer-reorg-threshold, proposer-reorg-parent-threshold, or proposer-reorg-epochs-since-finalization are provided override the config from the config.yaml
2. Add REORG_HEAD_WEIGHT_THRESHOLD, REORG_PARENT_WEIGHT_THRESHOLD, REORG_MAX_EPOCHS_SINCE_FINALIZATION to /eth/v1/config/spec

Additional Info

1. I considered possible removing the cli prop disable-proposer-reorgs but after going back to phase0 spec I can see that its language implies that calling get_proposer_head is optional thus I'm leaving it as is.
2. @michaelsproul suggested I make the re org props in chainspec not optional but I left it as is so I did not have to change the get_proposer_head logic in the consensus code.

Testing

in addition to unit tests, curled the spec api and got

{
...
  "REORG_HEAD_WEIGHT_THRESHOLD": "20",
  "REORG_PARENT_WEIGHT_THRESHOLD": "160",
  "REORG_MAX_EPOCHS_SINCE_FINALIZATION": "2"
...
}

[0xmrree]

made new rev for this based on feedback from: #8601 - mostly added defaults for the reorg in the Config class to avoid tweaking with existing config.yaml's - ready for review