[Kernel] Add specific exception subclasses for loadSnapshotAt version failures

[GabrielBBaldez]

Which Delta project/connector is this regarding?

• Kernel

Description

When loading a snapshot at a specific version, SnapshotManager currently signals both out-of-range failures with a generic KernelException, so callers can only tell them apart by string-matching the message.

This adds two typed subclasses of KernelException and returns them from the corresponding DeltaErrors factory methods:

• VersionToLoadAfterLatestCommitException — the requested version is higher than the latest commit (not materialized yet; typically recoverable by retrying).
• VersionTruncatedException — the requested version is lower than the earliest available commit because the log has been truncated (unrecoverable for that version).

Both extend KernelException, mirroring how DeltaErrors#missingCheckpoint already returns an InvalidTableException. Connectors can now catch the specific type instead of parsing the message — e.g. the delta-spark V2 CDC SparkMicroBatchStream can swallow VersionToLoadAfterLatestCommitException to wait for the version to be committed.

Resolves #6745.

How was this patch tested?

Updated the existing SnapshotManagerSuite cases that exercise these two paths (getLogSegmentForVersion: versionToLoad higher than possible and ... not constructable from history) to assert the specific exception type is thrown instead of the generic RuntimeException.

Does this PR introduce any user-facing changes?

No behavioral change: both new types extend KernelException, so existing catch (KernelException ...) keeps working and the messages are unchanged. Callers simply gain the option to catch the narrower types.