RFC: Add format_major_version and format_minor_version to thrift metadata

[alamb]

Rationale for this change

• Part of Define core features / compliance level #384

NOTE: there is an alternate RFC here

• RFC: Encode parquet-format minor_version in thrift metadata #581

As described on the mailing list thread about versions, there is currently no way for a parquet reader to know which if the many parquet features it may encounter in a particular file

The current version field in the thirft metadata is insufficient because:
2. There is no agreed upon definition of version and many writers use it incorrectly:

parquet-format/src/main/thrift/parquet.thrift

Lines 1368 to 1373 in 74001e4

	* As of December 2025, there is no agreed upon consensus of what constitutes
	* version 2 of the file. For maximum compatibility with readers, writers should
	* always populate "1" for version. For maximum compatibility with writers,
	* readers should accept "1" and "2" interchangeably. All other versions are
	* reserved for potential future use-cases.
	*/

1. Even if we agreed to use the version field, version "2" has several forward incompatible changes (see Document Parquet Features by Version parquet-site#186) meaning a reader doesn't know what features it may encounter

What changes are included in this PR?

Add net new format_major_version and format_minor_version fields to the thrift metadata to encode the version of parquet-format. Readers can use this field to determine what features it may encounter.

Open questions:

• Guidance for writing with maximum compatibility (set version to 2 and then use major/minor version?)
• Should new versions of parquet-format require writers to set this field?
• Would we ever change the version field?

These field would be ignored by older readers

Do these changes have PoC implementations?

Not yet