primitives: add ControlBlock constructor

primitives/src/coding.rs

@@ -496,7 +496,7 @@ impl ConsensusEncode for ControlBlock {
             self.leaf_version.to_consensus_u8() & self.output_key_parity.to_consensus_u8();
         first_byte.consensus_encode(writer)?;
 
-        counter += self.internal_key.consensus_encode(writer)?;
+        counter += self.internal_pk.consensus_encode(writer)?;
         for step in &self.merkle_branch {
             counter += step.consensus_encode(writer)?;
         }
@@ -526,7 +526,7 @@ impl ConsensusDecode for ControlBlock {
         Ok(ControlBlock {
             leaf_version,
             output_key_parity,
-            internal_key,
+            internal_pk: internal_key,
             merkle_branch,
         })
     }

primitives/src/taproot.rs

@@ -661,7 +661,24 @@ pub struct ControlBlock {
     /// XONLY).
     pub output_key_parity: Parity,
     /// The internal key.
-    pub internal_key: InternalPk,
+    pub internal_pk: InternalPk,
     /// The merkle proof of a script associated with this leaf.
     pub merkle_branch: TapMerklePath,
 }
+
+impl ControlBlock {
+    #[inline]
+    pub fn with(
+        leaf_version: LeafVer,
+        internal_pk: InternalPk,
+        output_key_parity: Parity,
+        merkle_branch: TapMerklePath,
+    ) -> Self {
+        ControlBlock {
+            leaf_version,
+            output_key_parity,
+            internal_pk,
+            merkle_branch,
+        }
+    }
+}