Page through the received routes, on the status page and in the API

/api/routes/received now returns one page: {routes, next_after,
prev_before}. Pages are in prefix order and begin at a prefix (after= or
before=), not at a count, so a table that changes between two pages does
not make them overlap or leave a gap. A page holds whole prefixes, about
`limit` routes' worth.

The table keeps prefixes in no order, so a page is found by looking at
every prefix once and keeping the nearest few; the routes of the others
are not touched (RibTable::for_each_prefix).

The status page shows about 100 routes with first / previous / next
links; the place is kept in the page's address with the lookup.

The response of /api/routes/received was an array before: this changes
its shape.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

crates/integration-tests/tests/aspa.rs

@@ -172,7 +172,7 @@ async fn test_a_leaked_route_is_refused_and_the_rest_are_taken() -> Result<()> {
         let request = client.get(format!("{base}{path}"));
         async move { Ok::<Value, eyre::Report>(request.send().await?.error_for_status()?.json().await?) }
     };
-    let routes = get("/api/routes/received").await?;
+    let routes = get("/api/routes/received").await?["routes"].take();
     let validity: Vec<(&str, &str)> = routes
         .as_array()
         .unwrap()
@@ -323,7 +323,7 @@ async fn test_a_peer_can_be_exempt_from_path_verification() -> Result<()> {
         .await?
         .json()
         .await?;
-    assert_eq!(routes[0]["aspa"], "invalid");
+    assert_eq!(routes["routes"][0]["aspa"], "invalid");
     assert!(server.refusals.peers().is_empty());
     Ok(())
 }