endpoint_storage compute_ctl integration (#11550)

Add `/lfc/(prewarm|offload)` routes to `compute_ctl` which interact with
endpoint storage.

Add `prewarm_lfc_on_startup` spec option which, if enabled, downloads
LFC prewarm data on compute startup.

Resolves: https://github.com/neondatabase/cloud/issues/26343

libs/utils/src/id.rs

@@ -295,6 +295,9 @@ pub struct TenantId(Id);
 
 id_newtype!(TenantId);
 
+/// If needed, reuse small string from proxy/src/types.rc
+pub type EndpointId = String;
+
 // A pair uniquely identifying Neon instance.
 #[derive(Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Serialize, Deserialize)]
 pub struct TenantTimelineId {