Manual finalization endpoint (#7059)

* Load block roots from fork choice where possible to avoid loading state from disk when serving block by range requests.

* Check if the start slot is newer than finalization (`start_slot >= finalized_slot`), and use fork choice in that case.

* force finalization endpoint

* cleanup

* Remove ds store

* Don't import blocks that conflict with the split

* Disconnect and ban peer if we get blocks conflicting manual checkpoint

* immediately commit state to cold db

* revert

* Fix descent from split check

* Add safety check to checkpoint when doing manual finalization.

---------

Co-authored-by: Jimmy Chen <jchen.tc@gmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
Co-authored-by: Pawan Dhananjay <pawandhananjay@gmail.com>

consensus/fork_choice/src/fork_choice.rs

@@ -1255,6 +1255,11 @@ where
             .is_finalized_checkpoint_or_descendant::<E>(block_root)
     }
 
+    pub fn is_descendant(&self, ancestor_root: Hash256, descendant_root: Hash256) -> bool {
+        self.proto_array
+            .is_descendant(ancestor_root, descendant_root)
+    }
+
     /// Returns `Ok(true)` if `block_root` has been imported optimistically or deemed invalid.
     ///
     /// Returns `Ok(false)` if `block_root`'s execution payload has been elected as fully VALID, if