Add version header for ssz responses

apis/beacon/blocks/block.v2.yaml

@@ -13,6 +13,9 @@ get:
   responses:
     "200":
       description: "Successful response"
+      headers:
+        Eth-Consensus-Version:
+          $ref: '../../../beacon-node-oapi.yaml#/components/headers/Eth-Consensus-Version'
       content:
         application/json:
           schema:
@@ -29,6 +32,7 @@ get:
                   - $ref: "../../../beacon-node-oapi.yaml#/components/schemas/Altair.SignedBeaconBlock"
         application/octet-stream:
           schema:
+
             description: "SSZ serialized block bytes. Use Accept header to choose this response type"
     "400":
       description: "The block ID supplied could not be parsed"

apis/debug/state.v2.yaml

@@ -14,6 +14,9 @@ get:
   responses:
     "200":
       description: Success
+      headers:
+        Eth-Consensus-Version:
+          $ref: '../../beacon-node-oapi.yaml#/components/headers/Eth-Consensus-Version'
       content:
         application/json:
           schema:

beacon-node-oapi.yaml

@@ -251,3 +251,11 @@ components:
       $ref: './types/http.yaml#/InternalError'
     CurrentlySyncing:
       $ref: './types/http.yaml#/CurrentlySyncing'
+
+  headers:
+    Eth-Consensus-Version:
+      description: Required in response so client can deserialize returned json or ssz data more effectively.
+      schema:
+        type: string
+        enum: [phase0, altair]
+        example: "phase0"