Restructure and re-organize Marconi modules

[kayvank]

• Renamed the module names from Marconi.JsonRpc to Network.JsonRpc
• Renamed marconi to marconi-chain-index
• Renamed rewindable-index package to marconi-core and changed corresponding module names accordingly
• Renamed marconi-mamba module names to match those of corresponding package name

Co-authored-by: koslambrou konstantinos.lambrou@iohk.io

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