More granular sync info RPC method

[onbjerg]

Describe the feature

We should add an endpoint to get more granular syncing info from Reth. It should return:

• The current checkpoint of each stage in an ordered array of { stage, checkpoint }
• The current target, e.g. just the latest FCU

Additional context

No response

[onbjerg]

cc @mattsse unsure if we should just stuff this into the reth_ namespace

[github-actions]

This issue is stale because it has been open for 21 days with no activity.

[mattsse]

we should but this under reth_ namespace

we need a few things first

1. rpc types
2. rpc module variant
3. then a handler implementation that monitors engine events

[kunal365roy]

Hey @mattsse, I'd love to take a stab at this!

[loocapro]

Can I take this?

[mattsse]

completed via #10042