[IPC] Delta Dictionary Flag Clarification for Multi-Batch IPC

ector=[], indexVector=[0, 3, 2] Thanks for your help! [1] https://github.com/apache/arrow/pull/38423 [2] https://github.com/apache/arrow/blob/main/format/Message.fbs#L134 [3] https://arrow.apache.org/docs/cpp/api/ipc.html#_CPPv4N5arrow3ipc15IpcWriteOptions18unify_dictionariesE -- Chris Larsen

[DISCUSS][IPC Format] Allow dictionary replacement in file format.

Hi folks, The IPC file format notes that it is "invalid to have more than one non-delta dictionary batch per dictionary ID (i.e. dictionary replacement is not supported)" but there is the "isDelta" flag that indicates replacement dictionaries are supported. However it isn't clear that this only ap