refactor(sql): add query_map_vec()

This also replaces some cases where flatten()
was used, effectively ignoring the errors.

src/net/dns.rs

@@ -630,7 +630,7 @@ async fn lookup_cache(
     let mut res = Vec::new();
     for cached_address in context
         .sql
-        .query_map(
+        .query_map_vec(
             "SELECT dns_cache.address
              FROM dns_cache
              LEFT JOIN connection_history
@@ -647,10 +647,6 @@ async fn lookup_cache(
                 let address: String = row.get(0)?;
                 Ok(address)
             },
-            |rows| {
-                rows.collect::<std::result::Result<Vec<String>, _>>()
-                    .map_err(Into::into)
-            },
         )
         .await?
     {