wallet: add_input_info to no longer do network requests

- wallet.add_input_info() previously had a fallback to download parent
  prev txs from the network (after a lookup in wallet.db failed).
  wallet.add_input_info() is not async, so the network request cannot
  be done cleanly there and was really just a hack.
- tx.add_info_from_wallet() calls wallet.add_input_info() on each txin,
  in which case these network requests were done sequentially, not concurrently
- the network part of wallet.add_input_info() is now split out into new method:
  txin.add_info_from_network()
- in addition to tx.add_info_from_wallet(), there is now also tx.add_info_from_network()
  - callers of old tx.add_info_from_wallet() should now called either
    - tx.add_info_from_wallet(), then tx.add_info_from_network(), preferably in that order
    - tx.add_info_from_wallet() alone is sufficient if the tx is complete,
      or typically when not in a signing context
- callers of wallet.bump_fee and wallet.dscancel are now expected to have already
  called tx.add_info_from_network(), as it cannot be done in a non-async context
  (but for the common case of all-inputs-are-ismine, bump_fee/dscancel should work regardless)
- PartialTxInput.utxo was moved to the baseclass, TxInput.utxo

electrum/address_synchronizer.py

@@ -138,9 +138,8 @@ class AddressSynchronizer(Logger, EventListener):
         return len(self._history_local.get(addr, ()))
 
     def get_txin_address(self, txin: TxInput) -> Optional[str]:
-        if isinstance(txin, PartialTxInput):
-            if txin.address:
-                return txin.address
+        if txin.address:
+            return txin.address
         prevout_hash = txin.prevout.txid.hex()
         prevout_n = txin.prevout.out_idx
         for addr in self.db.get_txo_addresses(prevout_hash):