Add PsbtInputExt::update_with_descriptor

This populates all relevant fields in a PSBT input according to a
descriptor. Includes previously not yet implemented logic for populating
bip32_derivation and tap_key_origins.

I renamed "PsbtExt::update_desc" to
"PsbtExt::update_input_with_descriptor" which uses the same logic as
update_with_descriptor internally but additionally does some sanity
checks. I removed scanning logic for update_desc because you can do it
with find_derivation_index_for_spk.

integration_test/src/test_desc.rs

@@ -13,7 +13,7 @@ use bitcoin::util::{psbt, sighash};
 use bitcoin::{self, Amount, OutPoint, SchnorrSig, Script, Transaction, TxIn, TxOut, Txid};
 use bitcoincore_rpc::{json, Client, RpcApi};
 use miniscript::miniscript::iter;
-use miniscript::psbt::PsbtExt;
+use miniscript::psbt::{PsbtInputExt, PsbtExt};
 use miniscript::{Descriptor, DescriptorTrait, Miniscript, ToPublicKey};
 use miniscript::{MiniscriptKey, ScriptContext};
 use std::collections::BTreeMap;
@@ -109,10 +109,10 @@ pub fn test_desc_satisfy(cl: &Client, testdata: &TestData, desc: &str) -> Witnes
         script_pubkey: addr.script_pubkey(),
     });
     let mut input = psbt::Input::default();
+    input.update_with_descriptor_unchecked(&desc).unwrap();
     input.witness_utxo = Some(witness_utxo.clone());
     psbt.inputs.push(input);
     psbt.outputs.push(psbt::Output::default());
-    psbt.update_desc(0, &desc, None).unwrap();
 
     // --------------------------------------------
     // Sign the transactions with all keys

src/descriptor/mod.rs

@@ -260,6 +260,19 @@ pub enum DescriptorType {
     Tr,
 }
 
+impl DescriptorType {
+    /// Whether this is a segwit descriptor.
+    ///
+    /// Returns true whether it is "native" segwit or "wrapped" p2sh segwit
+    pub fn is_segwit(&self) -> bool {
+        use self::DescriptorType::*;
+        match self {
+            Wpkh | ShWpkh | Wsh | ShWsh | ShWshSortedMulti | WshSortedMulti | Tr => true,
+            Bare | Sh | Pkh | ShSortedMulti => false,
+        }
+    }
+}
+
 impl<Pk: MiniscriptKey> Descriptor<Pk> {
     // Keys