DAL: implement basic snapshot export feature

What

Add a basic datadir export mecanism in DAL node.

Why

Extract/backup data from a node, and use it with another one

How

Read values that need to be exported and write them in the datadir you are exporting into.

Manually testing the MR

SYNOPSIS
       octez-dal-node snapshot export [--data-dir=DIR]
       [--max-published-level=INT] [--min-published-level=INT] [OPTION]… FILE

DESCRIPTION
       Export DAL node data to a snapshot file.

OPTIONS
       -d DIR, --data-dir=DIR
           The  directory  where  the  Octez DAL node will store all its data.
           Parent directories are created if necessary.

       --max-published-level=INT
           Maximum published level to include in the snapshot.

       --min-published-level=INT
           Minimum published level to include in the snapshot.

       FILE (required)
           Path to the snapshot file to export.

./octez-dal-node snapshot export --data-dir /tmp/data-dir /tmp/export
# Have a look at what is inside /tmp/export
./octez-dal-node run --data-dir /tmp/export
# Query some fresh data (new since the node started) and some old data (coming from the export)
# Play with --max-published-level and --min-published-level and check that excluded data are not exported

Summary by CodeRabbit

Release Notes

• New Features

  • Added snapshot export functionality to export DAL node store data, including slots, shards, and associated metadata
  • Supports optional filtering by publication level range for selective data export

• Refactor

  • Updated internal data storage to remove status field from skip-list cells
  • Enhanced store initialization with optional read-only mode support

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