feat(client): implement lifecycle operations and support reconnecting to existing sessions

[camory]

Pull Request Description

Summary

This PR introduces complete support for session retrieval and lifecycle management .
It expands the SessionHandle API, enhances the underlying gRPC mapping layer,.

This feature aligns the Java SDK with the full lifecycle exposed by the Sessions service (Create, Get, Pause, Resume, Cancel, Close, Purge, Delete).

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Motivation

Sessions in ArmoniK are long-lived entities and can be reused across client restarts.
Until now, the Java SDK only supported:

• openSession()
• Task submission

But not:

• reconnecting to an existing session
• performing lifecycle actions from the SDK
• obtaining structured lifecycle information (SessionState)

This PR completes the feature set and makes the Java SDK consistent with the official session lifecycle defined in ArmoniK.

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Changes

✔️ Public API

New in SessionHandle

All lifecycle operations are now available:

• cancel()
• pause()
• resume()
• close()
• purge()
• delete()

Each method:

• calls the matching gRPC RPC (CancelSession, PauseSession, etc.)
• returns a CompletionStage<SessionState>
• uses the new unified SessionState record

ArmoniKClient

• Added getSession(SessionId) and getSession(SessionId, BlobCompletionListener)
• Added deleteSession(SessionId) as a convenience API

SessionState

• New public record representing the complete state of a session:
  • status, submission flags, partition IDs
  • task configuration defaults
  • timestamps (created, cancelled, paused, closed, purged, deleted)
  • duration

Full Javadoc added.

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✔️ Testing

Mapping tests

Added SessionMapperTest to ensure correct mapping of:

• timestamps
• duration
• partition IDs
• task configuration
• null-handling

Wiring tests

Extended SessionHandleTest to cover all lifecycle RPCs with minimal, high-value assertions:

• verifies correct RPC invoked
• verifies correct sessionId passed
• verifies CompletionStage completes without exception
  (no redundant state assertions—mapping is already tested)

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Backward compatibility

This PR is fully backward compatible:

• No existing public APIs are changed
• All new APIs are purely additive
• Existing behavior of openSession() and task submission untouched

[aneojgurhem]

why is the delete here ?

[camory]

I have replaced it by closeSession()