Smash dkg into dkg, dkg-[recovery, promote, musig, pedpop]

promote and pedpop require dleq, which don't support no-std. All three should
be moved outside the Serai repository, per #597, as none are planned for use
and worth covering under our BBP.

crypto/dkg/promote/README.md

@@ -0,0 +1,12 @@
+# Distributed Key Generation - Promote
+
+This crate implements 'promotions' for keys from the [`dkg`](https://docs.rs/dkg) crate. A promotion
+takes a set of keys and maps it to a different `Ciphersuite`.
+
+This crate was originally part of the `dkg` crate, which was
+[audited by Cypher Stack in March 2023](
+  https://github.com/serai-dex/serai/raw/e1bb2c191b7123fd260d008e31656d090d559d21/audits/Cypher%20Stack%20crypto%20March%202023/Audit.pdf
+), culminating in commit
+[669d2dbffc1dafb82a09d9419ea182667115df06](
+  https://github.com/serai-dex/serai/tree/669d2dbffc1dafb82a09d9419ea182667115df06
+). Any subsequent changes have not undergone auditing.