Add no_std support to transcript, dalek-ff-group, ed448, ciphersuite, multiexp, schnorr, and monero-generators

transcript, dalek-ff-group, ed449, and ciphersuite are all usable with no_std
alone. The rest additionally require alloc.

Part of #279.

tests/no-std/src/lib.rs

@@ -0,0 +1,26 @@
+#![no_std]
+
+pub use flexible_transcript::*;
+
+pub mod dalek {
+  pub use dalek_ff_group::*;
+}
+pub mod ed448 {
+  pub use minimal_ed448::*;
+}
+
+pub use ciphersuite::*;
+
+pub use multiexp::*;
+
+// pub use dleq::*;
+pub use schnorr_signatures::*;
+
+/*
+pub use dkg::*;
+pub use modular_frost::*;
+pub use frost_schnorrkel::*;
+*/
+
+pub use monero_generators::*;
+// pub use monero_serai::*;