Have set_keys take signature_participants, not removed_participants

Now no one is removed from the DKG. Only `t` people publish the key however.

Uses a BitVec for an efficient encoding of the participants.

substrate/client/Cargo.toml

@@ -20,6 +20,8 @@ workspace = true
 zeroize = "^1.5"
 thiserror = { version = "1", optional = true }
 
+bitvec = { version = "1", default-features = false, features = ["alloc", "serde"] }
+
 hex = "0.4"
 scale = { package = "parity-scale-codec", version = "3" }
 serde = { version = "1", features = ["derive"], optional = true }

substrate/client/src/serai/validator_sets.rs

@@ -181,17 +181,14 @@ impl<'a> SeraiValidatorSets<'a> {
 
   pub fn set_keys(
     network: NetworkId,
-    removed_participants: sp_runtime::BoundedVec<
-      SeraiAddress,
-      sp_core::ConstU32<{ primitives::MAX_KEY_SHARES_PER_SET / 3 }>,
-    >,
     key_pair: KeyPair,
+    signature_participants: bitvec::vec::BitVec<u8, bitvec::order::Lsb0>,
     signature: Signature,
   ) -> Transaction {
     Serai::unsigned(serai_abi::Call::ValidatorSets(serai_abi::validator_sets::Call::set_keys {
       network,
-      removed_participants,
       key_pair,
+      signature_participants,
       signature,
     }))
   }