Implement `TRICE_DEFERRED_TRANSFER_MODE == TRICE_MULTI_PACK_MODE` for ring buffer

See also #306. TRICE_MULTI_PACK_MODE allows less transfer data. Especially when encryption is enabled this makes sense, because of the 64-bit package size granularity. TRICE_MULTI_PACK_MODE works already for double buffer (despite TRICE_SINGLE_PACK_MODE) but the ring buffer needs less RAM for being a bit slower. TRICE_MULTI_PACK_MODE has also a disadvantage: When a transfer package gets lost, this could affect several trice messages.