Creating redundancy getter which retrieves children chunks of an intermediate chunk and tries to recover missing data if there is any.

Its initialization happens by passing the data and parity shard addresses of the intermediate chunk having some parities greater than 0. To extract these addresses ChunkAddresses function was created in pkg/file/utils.go. along with ChunkPayloadSize function that identifies the effective size of an intermediate chunk. The redundancy level is encoded in the span of the intermediate chunk which is used to identify shard and parity reference counts in a chunk.
The getter also requires a storage.Putter interface for saving recovered chunks to the localStorage.

Let n indicate the data shard number and p for the parity number.
If a chunk is missing (or the faster requests strategy is enabled) then the recovery process will start n + k requests for data and parity shards and cancel all requests if n requests returned successfully. Data shards not returned in this process will be recovered and saved.

The redundancy getter is used by the file joiner that is responsible to read a file.

what is left:

• apply different strategies to the getter

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)

Motivation and Context (Optional)

Related Issue (Optional)

Screenshots (if appropriate):