graph/db+sqldb: implement UpdateEdgePolicy

In this commit, the various SQL queries are defined that we will need in
order to implement the SQLStore UpdateEdgePolicy method. Channel
policies can be "replaced" and so we use the upsert pattern for them
with the rule that any new channel policy must have a timestamp greater
than the previous one we persisted.

As is done for the KVStore implementation of the method, we use the
batch scheduler for this method.

sqldb/sqlc/queries/graph.sql

@@ -154,6 +154,17 @@ RETURNING id;
 SELECT * FROM channels
 WHERE scid = $1 AND version = $2;
 
+-- name: GetChannelAndNodesBySCID :one
+SELECT
+    c.*,
+    n1.pub_key AS node1_pub_key,
+    n2.pub_key AS node2_pub_key
+FROM channels c
+    JOIN nodes n1 ON c.node_id_1 = n1.id
+    JOIN nodes n2 ON c.node_id_2 = n2.id
+WHERE c.scid = $1
+  AND c.version = $2;
+
 -- name: HighestSCID :one
 SELECT scid
 FROM channels
@@ -183,3 +194,49 @@ INSERT INTO channel_extra_types (
     channel_id, type, value
 )
 VALUES ($1, $2, $3);
+
+/* ─────────────────────────────────────────────
+   channel_policies table queries
+   ─────────────────────────────────────────────
+*/
+
+-- name: UpsertEdgePolicy :one
+INSERT INTO channel_policies (
+    version, channel_id, node_id, timelock, fee_ppm,
+    base_fee_msat, min_htlc_msat, last_update, disabled,
+    max_htlc_msat, inbound_base_fee_msat,
+    inbound_fee_rate_milli_msat, signature
+) VALUES  (
+    $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13
+)
+ON CONFLICT (channel_id, node_id, version)
+    -- Update the following fields if a conflict occurs on channel_id,
+    -- node_id, and version.
+    DO UPDATE SET
+        timelock = EXCLUDED.timelock,
+        fee_ppm = EXCLUDED.fee_ppm,
+        base_fee_msat = EXCLUDED.base_fee_msat,
+        min_htlc_msat = EXCLUDED.min_htlc_msat,
+        last_update = EXCLUDED.last_update,
+        disabled = EXCLUDED.disabled,
+        max_htlc_msat = EXCLUDED.max_htlc_msat,
+        inbound_base_fee_msat = EXCLUDED.inbound_base_fee_msat,
+        inbound_fee_rate_milli_msat = EXCLUDED.inbound_fee_rate_milli_msat,
+        signature = EXCLUDED.signature
+WHERE EXCLUDED.last_update > channel_policies.last_update
+RETURNING id;
+
+/* ─────────────────────────────────────────────
+   channel_policy_extra_types table queries
+   ─────────────────────────────────────────────
+*/
+
+-- name: InsertChanPolicyExtraType :exec
+INSERT INTO channel_policy_extra_types (
+    channel_policy_id, type, value
+)
+VALUES ($1, $2, $3);
+
+-- name: DeleteChannelPolicyExtraTypes :exec
+DELETE FROM channel_policy_extra_types
+WHERE channel_policy_id = $1;