refactor: Replace `sessions`, `kernels`'s `status_history`'s type `map` with `list`

[jopemachine]

Refs #412, follow-up to #480. Related issue: https://github.com/lablup/backend.ai/pull/1116.

The current implementation saves only the most recent timestamp whenever status information in status_history is updated, and all previous information is deleted.

This PR prevents the loss of timestamp information by changing the data structure of sessions, kernels's status_history to List.

Previous format:

{
  "PENDING": "2024-01-01T00:00:05Z",
  "SCHEDULED": "2024-01-01T00:00:10Z",
  "PREPARING": "2024-01-01T00:00:12Z",
  "RESTARTING": "2024-01-01T00:30:00Z",
  "RUNNING": "2024-01-01T00:30:08Z",  // overwritten if restarted
}

New format:

[
  {"status": "PENDING", "timestamp": "2024-01-01T00:00:05Z"},
  {"status": "SCHEDULED", "timestamp": "2024-01-01T00:00:05Z"},
  {"status": "PREPARING", "timestamp": "2024-01-01T00:00:05Z"},
  {"status": "RUNNING", "timestamp": "2024-01-01T00:00:15Z"},  // preserved
  {"status": "RESTARTING", "timestamp": "2024-01-01T00:30:00Z"},
  {"status": "RUNNING", "timestamp": "2024-01-01T00:30:08Z"},
]

Checklist: (if applicable)

• [x] Milestone metadata specifying the target backport version
• [x] API server-client counterparts (e.g., manager API -> client SDK)

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📚 Documentation preview 📚: https://sorna--2113.org.readthedocs.build/en/2113/

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📚 Documentation preview 📚: https://sorna-ko--2113.org.readthedocs.build/ko/2113/