feat(da): RetrieveBatchesV2 method

[keruch]

Part of #930

This PR contains changes with respect to the generalized DA specification. This is the second part of the implementation following #929.

Changelog:

• Added batch encoding/decoding [1]
• Added RetrieveBatchesV2 method [2]

For Author:

• [x] Targeted PR against correct branch
• [x] Included the correct type prefix in the PR title
• [x] Linked to Github issue with discussion and accepted design
• [x] Targets only one github issue
• [x] Wrote unit and integration tests <-- is not needed in this PR
• [x] All CI checks have passed
• [x] Added relevant godoc comments

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For Reviewer:

• [ ] Confirmed the correct type prefix in the PR title
• [ ] Reviewers assigned
• [ ] Confirmed all author checklist items have been addressed

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After reviewer approval:

• [ ] In case targets main branch, PR should be squashed and merged.
• [ ] In case PR targets a release branch, PR should be rebased.