sdk: add is_interactive() method Signer trait (#18407)

(cherry picked from commit 2af5ec4f57)

Co-authored-by: Trent Nelson <trent@solana.com>

sdk/src/signer/keypair.rs

@@ -80,6 +80,10 @@ impl Signer for Keypair {
     fn try_sign_message(&self, message: &[u8]) -> Result<Signature, SignerError> {
         Ok(self.sign_message(message))
     }
+
+    fn is_interactive(&self) -> bool {
+        false
+    }
 }
 
 impl<T> PartialEq<T> for Keypair

sdk/src/signer/mod.rs

@@ -68,6 +68,8 @@ pub trait Signer {
     }
     /// Fallibly produces an Ed25519 signature over the provided `message` bytes.
     fn try_sign_message(&self, message: &[u8]) -> Result<Signature, SignerError>;
+    /// Whether the impelmentation requires user interaction to sign
+    fn is_interactive(&self) -> bool;
 }
 
 impl<T> From<T> for Box<dyn Signer>

sdk/src/signer/null_signer.rs

@@ -28,6 +28,10 @@ impl Signer for NullSigner {
     fn try_sign_message(&self, _message: &[u8]) -> Result<Signature, SignerError> {
         Ok(Signature::default())
     }
+
+    fn is_interactive(&self) -> bool {
+        false
+    }
 }
 
 impl<T> PartialEq<T> for NullSigner

sdk/src/signer/presigner.rs

@@ -46,6 +46,10 @@ impl Signer for Presigner {
             Err(PresignerError::VerificationFailure.into())
         }
     }
+
+    fn is_interactive(&self) -> bool {
+        false
+    }
 }
 
 impl<T> PartialEq<T> for Presigner

sdk/src/signer/signers.rs

@@ -10,6 +10,7 @@ pub trait Signers {
     fn try_pubkeys(&self) -> Result<Vec<Pubkey>, SignerError>;
     fn sign_message(&self, message: &[u8]) -> Vec<Signature>;
     fn try_sign_message(&self, message: &[u8]) -> Result<Vec<Signature>, SignerError>;
+    fn is_interactive(&self) -> bool;
 }
 
 macro_rules! default_keypairs_impl {
@@ -39,6 +40,10 @@ macro_rules! default_keypairs_impl {
             }
             Ok(signatures)
         }
+
+        fn is_interactive(&self) -> bool {
+            self.iter().any(|s| s.is_interactive())
+        }
     };
 }
 
@@ -118,6 +123,9 @@ mod tests {
         fn try_sign_message(&self, _message: &[u8]) -> Result<Signature, SignerError> {
             Ok(Signature::default())
         }
+        fn is_interactive(&self) -> bool {
+            false
+        }
     }
 
     struct Bar;
@@ -128,6 +136,9 @@ mod tests {
         fn try_sign_message(&self, _message: &[u8]) -> Result<Signature, SignerError> {
             Ok(Signature::default())
         }
+        fn is_interactive(&self) -> bool {
+            false
+        }
     }
 
     #[test]