Represents Arrow Features that might not have full support
within implementations. This is intended to be used in
1. A mechanism for readers of Arrow Streams
and files to understand that the stream or file makes
use of a feature that isn't supported or unknown to
the implementation (and therefore can meet the Arrow
forward compatibility guarantees).
2. A means of negotiating between a client and server
what features a stream is allowed to use. The enums
values here are intented to represent higher level
features, additional details maybe negotiated
with key-value pairs specific to the protocol.
Enums added to this list should be assigned power-of-two values
to facilitate exchanging and comparing bitmaps for supported