Spark: Add location overlap validation for SnapshotTableAction

[varun-lakhyani]

Description

Implements location overlap validation for SnapshotTableAction to prevent destination table location from overlapping with source table location.

Resolves TODO comment in SnapshotTableSparkAction.java:127 in spark v4.1.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Added unit tests covering snapshot and source location overlap scenarios:
  • Exact same location
  • Source as a subdirectory of destination
  • Destination as a subdirectory of source
  • Completely non-overlapping locations
• All CI checks pass (31/31)

Checklist

• Implementation follows existing code patterns and Iceberg contribution guidelines
• Code compiles without errors
• Test coverage added
• No breaking changes to public APIs

[RussellSpitzer]

Definitely needs a test case, not sure why windows would make testing impossible since our locations are stored as strings

[RussellSpitzer]

Iceberg errors follow this format

"Cannot X because Y (possibly fix Z)"

So in this case

Cannot create a snapshot at location ... because it would overlap with source table ... Overlapping snapshot and source would ....

[varun-lakhyani]

@RussellSpitzer

Iceberg errors follow this format

"Cannot X because Y (possibly fix Z)"

So in this case

Cannot create a snapshot at location ... because it would overlap with source table ... Overlapping snapshot and source would ....

Thanks for the feedback.
Added unit tests covering overlapping snapshot and source locations (same path, parent/child cases, and non-overlapping paths) and have updated the error message to follow the Iceberg format.

All CI checks are passing now.

[varun-lakhyani]

Iceberg errors follow this format

"Cannot X because Y (possibly fix Z)"

So in this case

Cannot create a snapshot at location ... because it would overlap with source table ... Overlapping snapshot and source would ....

@RussellSpitzer
I have addressed all your feedback - added tests and updated error formatting.
All CI checks passing. Would appreciate a review when you are available, Happy to make any changes if required.
Thanks