Add api methods to request blockchain config

   This PR adds two API methods:
   1. "/v2/blockchain/blocks/{block_id}/config/raw" returns
       a config stored in a particular block
   2. "/v2/blockchain/config/raw" returns the latest config

Author: aleksej-paschenko

api/openapi.json

@@ -2811,6 +2811,19 @@
     ],
     "type": "object"
    },
+   "RawBlockchainConfig": {
+    "properties": {
+     "config": {
+      "additionalProperties": true,
+      "example": {},
+      "type": "object"
+     }
+    },
+    "required": [
+     "config"
+    ],
+    "type": "object"
+   },
    "Refund": {
     "properties": {
      "origin": {
@@ -4672,6 +4685,35 @@
     ]
    }
   },
+  "/v2/blockchain/blocks/{block_id}/config/raw": {
+   "get": {
+    "description": "Get raw blockchain config from a specific block, if present.",
+    "operationId": "getRawBlockchainConfigFromBlock",
+    "parameters": [
+     {
+      "$ref": "#/components/parameters/blockchainBlockIDParameter"
+     }
+    ],
+    "responses": {
+     "200": {
+      "content": {
+       "application/json": {
+        "schema": {
+         "$ref": "#/components/schemas/RawBlockchainConfig"
+        }
+       }
+      },
+      "description": "blockchain config"
+     },
+     "default": {
+      "$ref": "#/components/responses/Error"
+     }
+    },
+    "tags": [
+     "Blockchain"
+    ]
+   }
+  },
   "/v2/blockchain/blocks/{block_id}/transactions": {
    "get": {
     "description": "Get transactions from block",
@@ -4725,6 +4767,30 @@
     ]
    }
   },
+  "/v2/blockchain/config/raw": {
+   "get": {
+    "description": "Get raw blockchain config",
+    "operationId": "getRawBlockchainConfig",
+    "responses": {
+     "200": {
+      "content": {
+       "application/json": {
+        "schema": {
+         "$ref": "#/components/schemas/RawBlockchainConfig"
+        }
+       }
+      },
+      "description": "blockchain config"
+     },
+     "default": {
+      "$ref": "#/components/responses/Error"
+     }
+    },
+    "tags": [
+     "Blockchain"
+    ]
+   }
+  },
   "/v2/blockchain/masterchain-head": {
    "get": {
     "description": "Get last known masterchain block",

api/openapi.yml

@@ -45,6 +45,23 @@ paths:
                 $ref: '#/components/schemas/Transactions'
         'default':
           $ref: '#/components/responses/Error'
+  /v2/blockchain/blocks/{block_id}/config/raw:
+    get:
+      description: Get raw blockchain config from a specific block, if present.
+      operationId: getRawBlockchainConfigFromBlock
+      tags:
+        - Blockchain
+      parameters:
+        - $ref: '#/components/parameters/blockchainBlockIDParameter'
+      responses:
+        '200':
+          description: blockchain config
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/RawBlockchainConfig'
+        'default':
+          $ref: '#/components/responses/Error'
   /v2/blockchain/transactions/{transaction_id}:
     get:
       description: Get transaction data
@@ -220,6 +237,21 @@ paths:
                 $ref: '#/components/schemas/BlockchainConfig'
         'default':
           $ref: '#/components/responses/Error'
+  /v2/blockchain/config/raw:
+    get:
+      description: Get raw blockchain config
+      operationId: getRawBlockchainConfig
+      tags:
+        - Blockchain
+      responses:
+        '200':
+          description: blockchain config
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/RawBlockchainConfig'
+        'default':
+          $ref: '#/components/responses/Error'
   /v2/blockchain/accounts/{account_id}/inspect:
     get:
       description: Blockchain account inspect
@@ -3148,6 +3180,16 @@ components:
           example: [ ]
           items:
             $ref: '#/components/schemas/TvmStackRecord'
+    RawBlockchainConfig:
+      type: object
+      required:
+        - config
+      properties:
+        config:
+          type: object
+          additionalProperties: true
+          example: { }
+
     BlockchainConfig:
       type: object
       required: