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/commands.py

@@ -762,6 +762,8 @@ class Commands:
         coins = wallet.get_spendable_coins(None)
         if domain_coins is not None:
             coins = [coin for coin in coins if (coin.prevout.to_str() in domain_coins)]
+        tx.add_info_from_wallet(wallet)
+        await tx.add_info_from_network(self.network)
         new_tx = wallet.bump_fee(
             tx=tx,
             txid=tx.txid(),