refactor: shared source inside chunked_by adapters

[msgmaxim]

Pull Request

Closes: PRO-925

Checklist

Please conduct a thorough self-review before opening the PR.

• I am confident that the code works.
• I have updated documentation where appropriate.

Summary

One downside of this approach is that shared is sometimes called more times than strictly necessary (when shared source was used by more than just the chunked_by adapter, e.g. on strictly_monotonic_source in btc witnesser). The alternative I considered is to make chunked_by adapters methods on SharedSource directly, but I think current solution is OK considering that shared adapter seems relatively lightweight, and moving calls to shared cleaned up the high level code a little.

[linear]

PRO-925 Use shared adapter inside the chunking adapters

In order to not duplicate the work of the upstream adapters after chunking, the chain source that's passed into the chunking adapter needs to be shared. Rather than have to remember this needs to be done, we should instead do the sharing inside the chunking adapters themselves so it can't be forgotten.

The reason for this is that the chunked adapters create a separate client and stream for each epoch, the shared adapter ensures they are all using the same underlying stream and client.

[codecov]

Codecov Report

Attention: 29 lines in your changes are missing coverage. Please review.

Comparison is base (1de7247) 72% compared to head (3fbb185) 71%.
Report is 6 commits behind head on main.

Files	Patch %	Lines
...ngine/src/witness/common/chain_source/extension.rs	0%	18 Missing ⚠️
engine/src/witness/eth.rs	0%	4 Missing ⚠️
engine/src/witness/btc.rs	0%	3 Missing ⚠️
engine/src/witness/dot.rs	0%	3 Missing ⚠️
engine/src/witness/eth/key_manager.rs	0%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##            main   #4232    +/-   ##
======================================
- Coverage     72%     71%    -0%     
======================================
  Files        384     384            
  Lines      63015   63185   +170     
  Branches   63015   63185   +170     
======================================
+ Hits       45074   45123    +49     
- Misses     15609   15728   +119     
- Partials    2332    2334     +2     

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[kylezs]

current solution is OK considering that shared adapter seems relatively lightweight

I agree, think it's fine if it's used somewhere it's not necessary for the benefit of never forgetting to include it (which is a worse consequence)