Expand remote keystore interface to allow for hybrid mode (#7628)

* update to latest master

* updates on docs, license, meta

* hide ssrs behind feature flag

* implement remaining functions on the server

* sign server line length fix

* fix tests

* fixup in-memory-keystore

* adding failsafe

* skipping ecdsa test for now

* remote keystore param

* remote sign urls made available

* integrating keystore remotes features

* don't forget the dependency

* remove old cruft

* reset local keystore

* applying suggestions

* Switch to single remote, minor grumbles

* minor grumbles, docs

substrate/primitives/core/src/crypto.rs

@@ -1029,6 +1029,7 @@ pub trait CryptoType {
 	Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash, Encode, Decode, PassByInner,
 	crate::RuntimeDebug
 )]
+#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
 pub struct KeyTypeId(pub [u8; 4]);
 
 impl From<u32> for KeyTypeId {
@@ -1058,10 +1059,12 @@ impl<'a> TryFrom<&'a str> for KeyTypeId {
 
 /// An identifier for a specific cryptographic algorithm used by a key pair
 #[derive(Debug, Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash, Encode, Decode)]
+#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
 pub struct CryptoTypeId(pub [u8; 4]);
 
 /// A type alias of CryptoTypeId & a public key
 #[derive(Debug, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash, Encode, Decode)]
+#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
 pub struct CryptoTypePublicPair(pub CryptoTypeId, pub Vec<u8>);
 
 #[cfg(feature = "std")]