add ReadStreamByKey rpc

[YangKian]

PR Description

Type of change

• New feature

Summary of the change and which issue is fixed

Main changes:
pseudocode for main read loop

while {
    nextRoundReads <- streamRecv
  
    if (nextRoundReads == 0) break
  
    // send cached records fist
    if (cachedRecords not empty) {
        streamSend cachedRecords
        nextRoundReads -= cachedSize
    }

    while (nextRoundReads > 0) {
        records <- decompress <$> logdeviceReader read
        (needSend, cached) <- split nextRoundReads records
        streamSend needSend
        nextRoundReads -= sendRecordSize
        update cache
    }
}

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Checklist

• I have run format.sh under script
• I have commented my code, particularly in hard-to-understand areas
• New and existing unit tests pass locally with my changes