hsmd/db: backfill pubkey information so that psbts signing works

the way we use PSBTs to sign things requires that we have the
scriptpubkey available on the utxo so we can populate the witness-utxo
field with it.

this causes problems if we don't already have the scriptpubkey cached in
the database, as in *some* cases we require a round trip to the HSM to
populate them

to get over this hump, we backfill any and all missing scriptpubkey
information for the utxo's that we hold in our wallet.

this will allow us to clean up the NULL handling of missing
scriptpubkeys.

tests/test_db.py

@@ -180,6 +180,76 @@ def test_last_tx_psbt_upgrade(node_factory, bitcoind):
     bitcoind.rpc.decoderawtransaction(last_txs[1].hex())
 
 
+@unittest.skipIf(os.getenv('TEST_DB_PROVIDER', 'sqlite3') != 'sqlite3', "This test is based on a sqlite3 snapshot")
+@unittest.skipIf(TEST_NETWORK != 'regtest', "The network must match the DB snapshot")
+def test_backfill_scriptpubkeys(node_factory, bitcoind):
+    bitcoind.generate_block(214)
+
+    script_map = [
+        {
+            "txid": "2513F3340D493489811EAB440AC05650B5BC06290358972EB6A55533A9EED96A",
+            "scriptpubkey": "001438C10854C11E10CB3786460143C963C8530DF891",
+        }, {
+            "txid": "E380E18B6E810A464634B3A94B95AAA06B36A8982FD9D9D294982726EDC77DD3",
+            "scriptpubkey": "001407DB91DA65EF06B385F4EA20BA05FAF286165C0B",
+        }, {
+            "txid": "E9AE7C9A346F9B9E35868176F311F3F2EE5DB8B94A065963E26954E119C49A79",
+            "scriptpubkey": "00147E5B5C8F4FC1A9484E259F92CA4CBB7FA2814EA4",
+        }, {
+            "txid": "4C88F50BF00518E4FE3434ACA42351D5AC5FEEE17C35595DFBC3D1F4279F6EC1",
+            "scriptpubkey": "0014D0EAC62FDCEE2D1881259BE9CDA4C43DE9050DB8",
+        }, {
+            "txid": "55265C3CAFE98C355FE0A440DCC005CF5C3145280EAD44D6B903A45D2DF3619C",
+            "scriptpubkey": "0014D0EAC62FDCEE2D1881259BE9CDA4C43DE9050DB8",
+        }, {
+            "txid": "06F6D1D29B175146381EAB59924EC438572D18A3701F8E4FDF4EE17DE78D31E3",
+            "scriptpubkey": "A9149551336F1E360F5AFB977F24CE72C744A82463D187",
+        }, {
+            "txid": "91BCEC7867F3F97F4F575D1D9DEDF5CF22BDDE643B36C2D9E6097048334EE32A",
+            "scriptpubkey": "0014DFA9D65F06088E922A661C29797EE616F793C863",
+        },
+    ]
+
+    # Test the first time, all entries are with option_static_remotekey
+    l1 = node_factory.get_node(node_id=3, dbfile='pubkey_regen.sqlite.xz')
+    results = l1.db_query('SELECT hex(prev_out_tx) AS txid, hex(scriptpubkey) AS script FROM outputs')
+    scripts = [{'txid': x['txid'], 'scriptpubkey': x['script']} for x in results]
+    for exp, actual in zip(script_map, scripts):
+        assert exp == actual
+
+    # Test again, without option_static_remotekey
+    script_map_2 = [
+        {
+            "txid": "FF89677793AC6F39E4AEB9D393B45F1E3D902CBFA26B521C5C438345A6D36E54",
+            "scriptpubkey": "001438C10854C11E10CB3786460143C963C8530DF891",
+        }, {
+            "txid": "0F0685CCEE067638629B1CB27111EB0E15E19B75B1F5D368FC10D216D48FF4A5",
+            "scriptpubkey": "001407DB91DA65EF06B385F4EA20BA05FAF286165C0B",
+        }, {
+            "txid": "822466946527F940A53B823C507A319FDC91CCE55E455D916C9FE13B982058FA",
+            "scriptpubkey": "00144A94D23CD5A438531AADD86A0237FE11B9EA4E09",
+        }, {
+            "txid": "383145E40C8A9F45A0409E080DA5861C9E754B1EC8DD5EFA8A84DEB158E61C88",
+            "scriptpubkey": "0014D0EAC62FDCEE2D1881259BE9CDA4C43DE9050DB8",
+        }, {
+            "txid": "D221BE9B7CDB5FDB58B34D59B30304B7C4C2DF9C3BF73A4AE0E0265642FEC560",
+            "scriptpubkey": "0014D0EAC62FDCEE2D1881259BE9CDA4C43DE9050DB8",
+        }, {
+            "txid": "420F06E91CEE996D8E75E0565D776A96E8959ECA11E799FFE14522C2D43CCFA5",
+            "scriptpubkey": "A9149551336F1E360F5AFB977F24CE72C744A82463D187",
+        }, {
+            "txid": "9F6127316EBED57E7702A4DF19D6FC0EC23A8FAB9BC0D4AD82C29D3F93C525CD",
+            "scriptpubkey": "0014E445493A382C798AF195724DFF67DE4C9250AEC6",
+        }
+    ]
+
+    l2 = node_factory.get_node(node_id=3, dbfile='pubkey_regen_commitment_point.sqlite3.xz')
+    results = l2.db_query('SELECT hex(prev_out_tx) AS txid, hex(scriptpubkey) AS script FROM outputs')
+    scripts = [{'txid': x['txid'], 'scriptpubkey': x['script']} for x in results]
+    for exp, actual in zip(script_map_2, scripts):
+        assert exp == actual
+
+
 @unittest.skipIf(VALGRIND and not DEVELOPER, "Without developer valgrind will complain about debug symbols missing")
 def test_optimistic_locking(node_factory, bitcoind):
     """Have a node run against a DB, then change it under its feet, crashing it.