Allow reading more than 32k Parquet row groups

[etseidl]

Which issue does this PR close?

• Closes parquet reader fails to read files with more than 32767 row groups when RowGroup.ordinal is absent #10129.

Rationale for this change

The parquet crate will error if more than 32767 row groups are present in the file. This is a limit imposed on write when encryption is in use, but there is no other limit on the number of row groups beyond that imposed by the Thrift compact protocol.

What changes are included in this PR?

This changes the ordinal field of the RowGroupMetaData from an i16 to i32. This allows reading up to the maximum number of row groups allowed by Thrift. On write, the ordinal on the RowGroup will not be written if more than 32k row groups are present.

Are these changes tested?

Yes

Are there any user-facing changes?

Yes, RowGroupMetaData::ordinal now returns Option<i32> and RowGroupMetaDataBuilder::set_ordinal takes Option<i32>.

[etseidl]

If this is needed sooner, I can revert the public changes and add an i32 accessor for use by the row numbering.