op-program: Pass required block hash to OutputByRoot rather than to L2Source constructor

[ajsutton]

Description

Removes the need to know the agreed block hash for each L2 chain before constructing the L2Source instance. When going multi-chain we'll calculate the L2 block number from the agreed super root prestate timestamp rather than having the L2 head hash passed in as an argument.

Tests

Tests continue working.

[codecov]

Codecov Report

Attention: Patch coverage is 47.36842% with 10 lines in your changes missing coverage. Please review.

Project coverage is 42.94%. Comparing base (3d3deab) to head (510c902).

Files with missing lines	Patch %	Lines
op-program/host/prefetcher/prefetcher.go	12.50%	7 Missing ⚠️
op-program/host/common/l2_source.go	60.00%	2 Missing ⚠️
op-program/host/host.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #13716      +/-   ##
===========================================
- Coverage    47.21%   42.94%   -4.28%     
===========================================
  Files          958      792     -166     
  Lines        80026    70659    -9367     
  Branches       766        0     -766     
===========================================
- Hits         37787    30342    -7445     
+ Misses       39343    37685    -1658     
+ Partials      2896     2632     -264     

Flag	Coverage Δ
cannon-go-tests-32	?
cannon-go-tests-64	?
contracts-bedrock-tests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
op-program/host/common/l2_client.go	70.00% <100.00%> (+22.38%)	⬆️
op-program/host/prefetcher/retry.go	100.00% <100.00%> (ø)
op-program/host/host.go	5.71% <0.00%> (ø)
op-program/host/common/l2_source.go	35.95% <60.00%> (ø)
op-program/host/prefetcher/prefetcher.go	62.18% <12.50%> (-0.79%)	⬇️

... and 171 files with indirect coverage changes