Internal support for linking any number of IP Pools and Silos.

- Add database queries for linking any number of IP Pools to the Oxide
  internal Silo, rather than assuming there's just one.
- Rework queries for linking / unlinking IP Pool and Silo, making them
  concurrency-safe and preventing deletion when there are IPs or we're
  trying to delete the last internal IP Pool.
- The public API does not change here. We're still assuming exactly one
  IP Pool per IP version for internal usage, and not allowing the link
  or pool to appear in the API. That'll be a follow-up commit.
- Fixes #8948

Author: bnaecker

common/src/api/external/http_pagination.rs

@@ -382,6 +382,15 @@ pub enum PaginatedBy<'a> {
     Name(DataPageParams<'a, Name>),
 }
 
+impl<'a> PaginatedBy<'a> {
+    pub fn limit(&self) -> NonZeroU32 {
+        match self {
+            PaginatedBy::Id(inner) => inner.limit,
+            PaginatedBy::Name(inner) => inner.limit,
+        }
+    }
+}
+
 impl<T: Clone + Debug + DeserializeOwned + JsonSchema + PartialEq + Serialize>
     ScanParams for ScanByNameOrId<T>
 {

nexus/db-model/src/ip_pool.rs

@@ -77,7 +77,9 @@ impl From<IpVersion> for shared::IpVersion {
 /// IP pools can be external or internal. External IP pools can be associated
 /// with a silo or project so that instance IP allocation draws from that pool
 /// instead of a system pool.
-#[derive(Queryable, Insertable, Selectable, Clone, Debug, Resource)]
+#[derive(
+    Queryable, Insertable, Selectable, Clone, Debug, Resource, PartialEq,
+)]
 #[diesel(table_name = ip_pool)]
 pub struct IpPool {
     #[diesel(embed)]