feat: add decoding methods

[NazariiDenha]

Purpose or design rationale of this PR

Describe your change. Make sure to answer these three questions: What does this PR do? Why does it do it? How does it do it?

Implement some decoding method, that will be used by l2geth during the process of syncing from DA

PR title

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• build: Changes that affect the build system or external dependencies (example scopes: yarn, eslint, typescript)
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• docs: Documentation-only changes
• feat: A new feature
• fix: A bug fix
• perf: A code change that improves performance
• refactor: A code change that doesn't fix a bug, or add a feature, or improves performance
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
• test: Adding missing tests or correcting existing tests

Breaking change label

Does this PR have the breaking-change label?

• No, this PR is not a breaking change
• Yes

[NazariiDenha]

I will also add some tests later

[NazariiDenha]

I will add decoding for codecv2 and then will be ready for review

[NazariiDenha]

ready for review

[roynalnaruto]

Some refactoring suggestions, questions and request for more inline documentation

[jonastheis]

Let's get this merged and then integrate into #25. Which means we need to revisit the implementation anyway. Therefore, I think this PR doesn't need to be perfect

[roynalnaruto]

A few minor suggestions and nit-picks.

[0xmountaintop]

This PR is tested with scroll-tech/go-ethereum#1013, @colinlyguo do you have time to review this PR so that we can merge it?

[colinlyguo]

This PR is tested with scroll-tech/go-ethereum#1013, @colinlyguo do you have time to review this PR so that we can merge it?

LGTM. and approved.

[colinlyguo]

Let's get this merged and then integrate into #25. Which means we need to revisit the implementation anyway. Therefore, I think this PR doesn't need to be perfect

agree.