Define timestamp ordering for int96 timestamp columns

[rahulketch]

Describe the enhancement requested

int96 is used as the default timestamp in spark. Timestamp filters are extremely common and lack of ordering and stats limit optimization opportunities
See also:
apache/parquet-java#3242
apache/arrow-rs#7686
https://lists.apache.org/thread/6fm50b3pmh6mz659jb5wx5vzmvwccz1n

[alamb]

Here is a PR that attempts to clarify the current status (does not attempt to actually define the ordering):

• GH-502: Clarify Int96 status and add recommended ordering #504

[alamb]

Here is a document with background clarification as well:

• https://docs.google.com/document/d/1Ox0qHYBgs_3-pNqn9V8zVQm_W6qP0lsbd2XwQnQVz1Y/edit?tab=t.0#heading=h.nx463wi3cktx