graph/db+sqldb: implement FetchChannelEdgesByOutpoint/SCID

And run `TestEdgeInsertionDeletion` against our SQL backends.

sqldb/sqlc/queries/graph.sql

@@ -262,6 +262,51 @@ ORDER BY
         ELSE COALESCE(cp2.last_update, 0)
         END ASC;
 
+-- name: GetChannelByOutpointWithPolicies :one
+SELECT
+    sqlc.embed(c),
+
+    n1.pub_key AS node1_pubkey,
+    n2.pub_key AS node2_pubkey,
+
+    -- Node 1 policy
+    cp1.id AS policy_1_id,
+    cp1.node_id AS policy_1_node_id,
+    cp1.version AS policy_1_version,
+    cp1.timelock AS policy_1_timelock,
+    cp1.fee_ppm AS policy_1_fee_ppm,
+    cp1.base_fee_msat AS policy_1_base_fee_msat,
+    cp1.min_htlc_msat AS policy_1_min_htlc_msat,
+    cp1.max_htlc_msat AS policy_1_max_htlc_msat,
+    cp1.last_update AS policy_1_last_update,
+    cp1.disabled AS policy_1_disabled,
+    cp1.inbound_base_fee_msat AS policy1_inbound_base_fee_msat,
+    cp1.inbound_fee_rate_milli_msat AS policy1_inbound_fee_rate_milli_msat,
+    cp1.signature AS policy_1_signature,
+
+    -- Node 2 policy
+    cp2.id AS policy_2_id,
+    cp2.node_id AS policy_2_node_id,
+    cp2.version AS policy_2_version,
+    cp2.timelock AS policy_2_timelock,
+    cp2.fee_ppm AS policy_2_fee_ppm,
+    cp2.base_fee_msat AS policy_2_base_fee_msat,
+    cp2.min_htlc_msat AS policy_2_min_htlc_msat,
+    cp2.max_htlc_msat AS policy_2_max_htlc_msat,
+    cp2.last_update AS policy_2_last_update,
+    cp2.disabled AS policy_2_disabled,
+    cp2.inbound_base_fee_msat AS policy2_inbound_base_fee_msat,
+    cp2.inbound_fee_rate_milli_msat AS policy2_inbound_fee_rate_milli_msat,
+    cp2.signature AS policy_2_signature
+FROM channels c
+    JOIN nodes n1 ON c.node_id_1 = n1.id
+    JOIN nodes n2 ON c.node_id_2 = n2.id
+    LEFT JOIN channel_policies cp1
+        ON cp1.channel_id = c.id AND cp1.node_id = c.node_id_1 AND cp1.version = c.version
+    LEFT JOIN channel_policies cp2
+        ON cp2.channel_id = c.id AND cp2.node_id = c.node_id_2 AND cp2.version = c.version
+WHERE c.outpoint = $1 AND c.version = $2;
+
 -- name: HighestSCID :one
 SELECT scid
 FROM channels
@@ -540,3 +585,11 @@ SELECT *
 FROM zombie_channels
 WHERE scid = $1
 AND version = $2;
+
+-- name: IsZombieChannel :one
+SELECT EXISTS (
+    SELECT 1
+    FROM zombie_channels
+    WHERE scid = $1
+    AND version = $2
+) AS is_zombie;