P3569 R0 Split define_aggregate from Reflection

[wg21bot]

P3569R0 Split define_aggregate from Reflection (Shafik Yaghmour, Aaron Ballman, Erich Keane, Corentin Jabot, Vlad Serebrennikov)

[inbal2l]

Adding LEWG for tracking.

[hanickadot]

EWG discussed this paper in Hagenberg.

P3569R0: Split substitute out of P2996.

SF	F	N	A	SA
5	5	2	16	13

Consensus against.

P3569R0: Split define_aggregate out of P2996.

SF	F	N	A	SA
8	6	8	11	8

Not consensus.