feat: erasure encoder

[nugaon]

• NewHashTrieWriter is responsible for writing chunk tree -> we should add parity chunks for intermediate levels too
  • change children reference serialization according to rsParity
  • cache effective chunks and add RS parities.
  • encode used redundancy level into chunk span
• created redundancy package in file for adding erasure coded data to files

Missing parts:

• replace RS Parity parameter in requests with high level abstraction (4 levels),
• span encoding intermediate level
• add parity chunks to intermediate levels,
• handle RS encoding when it is not a full chunk,
• edge-case handling at encrypted chunks,
• table
• updated openAPI docs
• add tests.

Checklist

• I have read the coding guide.
• My change requires a documentation update, and I have done it.
• I have added tests to cover my changes.
• I have filled out the description and linked the related issues.

Description

Open API Spec Version Changes (if applicable)

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