Rename is_finalized to is_finalizable

I really liked the is_complete naming, but that was changed earlier in b0f3992
Was also suggested by Andrew #929 (comment)

src/util/psbt/map/output.rs

@@ -194,7 +194,7 @@ impl TryFrom<TaprootBuilder> for TapTree {
     /// A [`TapTree`] iff the `builder` is complete, otherwise return [`IncompleteTapTree`]
     /// error with the content of incomplete `builder` instance.
     fn try_from(builder: TaprootBuilder) -> Result<Self, Self::Error> {
-        if !builder.is_finalized() {
+        if !builder.is_finalizable() {
             Err(IncompleteTapTree::NotFinalized(builder))
         } else if builder.has_hidden_nodes() {
             Err(IncompleteTapTree::HiddenParts(builder))

src/util/psbt/serialize.rs

@@ -343,7 +343,7 @@ impl Deserialize for TapTree {
             builder = builder.add_leaf_with_ver(*depth, script, leaf_version)
                 .map_err(|_| encode::Error::ParseFailed("Tree not in DFS order"))?;
         }
-        if builder.is_finalized() && !builder.has_hidden_nodes() {
+        if builder.is_finalizable() && !builder.has_hidden_nodes() {
             Ok(TapTree(builder))
         } else {
             Err(encode::Error::ParseFailed("Incomplete taproot Tree"))

src/util/taproot.rs

@@ -441,7 +441,7 @@ impl TaprootBuilder {
     }
 
     /// Checks if the builder has finalized building a tree.
-    pub fn is_finalized(&self) -> bool {
+    pub fn is_finalizable(&self) -> bool {
         self.branch.len() == 1 && self.branch[0].is_some()
     }
 
@@ -452,8 +452,8 @@ impl TaprootBuilder {
 
     /// Creates a [`TaprootSpendInfo`] with the given internal key.
     ///
-    /// Returns the unmodified builder as Err if the builder is not finalized.
-    /// See also [`TaprootBuilder::is_finalized`]
+    /// Returns the unmodified builder as Err if the builder is not finalizable.
+    /// See also [`TaprootBuilder::is_finalizable`]
     pub fn finalize<C: secp256k1::Verification>(
         mut self,
         secp: &Secp256k1<C>,