Delete RuntimeVariableList::from_vec (#7930)

This method is a footgun because it truncates the list. It is the source of a recent bug:

- https://github.com/sigp/lighthouse/pull/7927


  - Delete uses of `RuntimeVariableList::from_vec` and replace them with `::new` which does validation and can fail.
- Propagate errors where possible, unwrap in tests and use `expect` for obviously-safe uses (in `chain_spec.rs`).

beacon_node/lighthouse_network/src/rpc/methods.rs

@@ -481,20 +481,22 @@ pub struct BlocksByRootRequest {
 }
 
 impl BlocksByRootRequest {
-    pub fn new(block_roots: Vec<Hash256>, fork_context: &ForkContext) -> Self {
+    pub fn new(block_roots: Vec<Hash256>, fork_context: &ForkContext) -> Result<Self, String> {
         let max_request_blocks = fork_context
             .spec
             .max_request_blocks(fork_context.current_fork_name());
-        let block_roots = RuntimeVariableList::from_vec(block_roots, max_request_blocks);
-        Self::V2(BlocksByRootRequestV2 { block_roots })
+        let block_roots = RuntimeVariableList::new(block_roots, max_request_blocks)
+            .map_err(|e| format!("BlocksByRootRequestV2 too many roots: {e:?}"))?;
+        Ok(Self::V2(BlocksByRootRequestV2 { block_roots }))
     }
 
-    pub fn new_v1(block_roots: Vec<Hash256>, fork_context: &ForkContext) -> Self {
+    pub fn new_v1(block_roots: Vec<Hash256>, fork_context: &ForkContext) -> Result<Self, String> {
         let max_request_blocks = fork_context
             .spec
             .max_request_blocks(fork_context.current_fork_name());
-        let block_roots = RuntimeVariableList::from_vec(block_roots, max_request_blocks);
-        Self::V1(BlocksByRootRequestV1 { block_roots })
+        let block_roots = RuntimeVariableList::new(block_roots, max_request_blocks)
+            .map_err(|e| format!("BlocksByRootRequestV1 too many roots: {e:?}"))?;
+        Ok(Self::V1(BlocksByRootRequestV1 { block_roots }))
     }
 }
 
@@ -506,12 +508,13 @@ pub struct BlobsByRootRequest {
 }
 
 impl BlobsByRootRequest {
-    pub fn new(blob_ids: Vec<BlobIdentifier>, fork_context: &ForkContext) -> Self {
+    pub fn new(blob_ids: Vec<BlobIdentifier>, fork_context: &ForkContext) -> Result<Self, String> {
         let max_request_blob_sidecars = fork_context
             .spec
             .max_request_blob_sidecars(fork_context.current_fork_name());
-        let blob_ids = RuntimeVariableList::from_vec(blob_ids, max_request_blob_sidecars);
-        Self { blob_ids }
+        let blob_ids = RuntimeVariableList::new(blob_ids, max_request_blob_sidecars)
+            .map_err(|e| format!("BlobsByRootRequestV1 too many blob IDs: {e:?}"))?;
+        Ok(Self { blob_ids })
     }
 }
 
@@ -526,9 +529,10 @@ impl<E: EthSpec> DataColumnsByRootRequest<E> {
     pub fn new(
         data_column_ids: Vec<DataColumnsByRootIdentifier<E>>,
         max_request_blocks: usize,
-    ) -> Self {
-        let data_column_ids = RuntimeVariableList::from_vec(data_column_ids, max_request_blocks);
-        Self { data_column_ids }
+    ) -> Result<Self, &'static str> {
+        let data_column_ids = RuntimeVariableList::new(data_column_ids, max_request_blocks)
+            .map_err(|_| "DataColumnsByRootRequest too many column IDs")?;
+        Ok(Self { data_column_ids })
     }
 
     pub fn max_requested(&self) -> usize {