fix(csharp): surface closed/expired sessions as a clear, typed error

[jadewang-db]

When a server-side session is closed or times out due to inactivity, the next Thrift call returns HTTP 400 "Invalid SessionHandle". The driver previously surfaced this as a misleading "An unexpected error occurred while fetching results / Couldn't connect to server" wrapper, and kept reusing the now-stale handle so every subsequent call failed the same opaque way until the caller disposed and re-created the connection.

Tier 1 (clear, typed error): detect the closed/expired-session signature and surface it as a typed DatabricksSessionExpiredException (AdbcStatusCode.InvalidState) with a clear message, preserving the original error as InnerException for diagnostics.

Tier 2 (fail fast): mark the connection's session invalid on first detection so subsequent statements fail fast with the same typed error instead of reusing the dead handle.

Detection walks the inner/aggregate exception chain for the stable server phrase "Invalid SessionHandle" (covers both the inactivity-timeout "Session [..] is closed" and explicit-close variants) and is careful not to misclassify connectivity errors or invalid operation handles.

Tests:

• Unit tests for the classifier (no workspace required, runs in CI).
• E2E test that reproduces the condition on demand by closing the session out-of-band, asserting both the typed Tier 1 error and Tier 2 fast-fail.

[msrathore-db]

is there no better way to identify this?

[msrathore-db]

Tier 2 fast-fails emit no telemetry

[msrathore-db]

We need to do the same for metadata and fetch paths also right?

[eric-wang-1990]

I think this logic should happen in the HiveServer2Connection class: https://github.com/adbc-drivers/hiveserver2/blob/main/csharp/src/AdbcDrivers.HiveServer2/Hive2/HiveServer2Statement.cs#L360C85-L360C105.

We can change the SessionHandle to something like this:

internal TSessionHandle SessionHandle
{
    get
    {
        if (_isSessionInvalidated)
        {
            throw new AdbcException(
                "The session was closed by the server.");
        }

        return _sessionHandle
            ?? throw new AdbcException(
                "Connection is not open.");
    }

    private set => _sessionHandle = value;
}

Then this will guard for every Thrift operation and we do not need to manually edit the callsite one by one.
WDYT?