WIP: remaining fetcher hints

[zobront]

Description

This is a WIP PR to address #249. Since #232 added a few of the desired hint types, the remaining ones to tackle in this PR will be:

• L1Blob
• L2Transactions

Also including some small changes to the existing code (fix for output root calculation and small update to comments).

Tests

N/A

Additional context

• L2Transactions implementation in op-program: https://github.com/ethereum-optimism/optimism/blob/develop/op-program/client/l2/oracle.go#L73-L83
• L1Blob implementation in op-program: https://github.com/ethereum-optimism/optimism/blob/3aeb6bdd3efe798713098f890359513eaaa91522/op-program/client/l1/oracle.go#L99

Metadata

• Fixes feat(host): Implement missing hint types in prefetch() #249

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 73.7%. Comparing base (b24f145) to head (a8b0a35).

Files	Patch %	Lines
bin/host/src/fetcher/mod.rs	0.0%	5 Missing ⚠️

Additional details and impacted files

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