Added MetadataFile to store internal informations about Neptune objects

[Raalsky]

The idea is to store information about internal container structure, operations version etc. The goal is to simplify the implementation of neptune.cli that currently it needs to use a lot of assumptions to support old client structures.

Sample content:

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Before submitting checklist

• Did you update the CHANGELOG? (not for test updates, internal changes/refactors or CI/CD setup)
• Did you ask the docs owner to review all the user-facing changes?

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Files	Coverage Δ
src/neptune/internal/metadata_file.py	100.00% <100.00%> (ø)
.../operation_processors/async_operation_processor.py	84.18% <100.00%> (+0.58%)	⬆️
...peration_processors/offline_operation_processor.py	83.78% <100.00%> (+1.96%)	⬆️
...l/operation_processors/sync_operation_processor.py	84.61% <100.00%> (+3.36%)	⬆️
src/neptune/internal/operation_processors/utils.py	84.61% <84.61%> (ø)

... and 104 files with indirect coverage changes

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