backport: merge bitcoin#24989, #26135, #26150, #26159, #26489, #26825, #28127, #29275, #29263, partial bitcoin#24831, #27790, #27978 (c++20 backports: part 1)

backport: merge bitcoin#24989, #26135, #26150, #26159, #26489, #26825, #28127, #29275, #29263, partial bitcoin#24831, #27790, #27978 (c++20 backports: part 1) #1268