Cleanup api.createType d.ts, add createType to registry (#1929)

* Cleanup api.createType d.ts, add createType to registry

* CHANGELOG

packages/types/src/create/registry.ts

@@ -14,6 +14,7 @@ import { defaultExtensions, expandExtensionTypes, findUnknownExtensions } from '
 import { EventData } from '../generic/Event';
 import Unconstructable from '../primitive/Unconstructable';
 import { createClass, getTypeClass } from './createClass';
+import { createType } from './createType';
 import { getTypeDef } from './getTypeDef';
 
 // create error mapping from metadata
@@ -127,6 +128,13 @@ export class TypeRegistry implements Registry {
       : formatBalance.getDefaults().unit;
   }
 
+  /**
+   * @description Creates an instance of a type as registered
+   */
+  public createType <K extends keyof InterfaceTypes> (type: K, ...params: any[]): InterfaceTypes[K] {
+    return createType(this, type, ...params);
+  }
+
   // find a specific call
   public findMetaCall (callIndex: Uint8Array): CallFunction {
     const hexIndex = u8aToHex(callIndex);

packages/types/src/types/registry.ts

@@ -92,6 +92,7 @@ export interface Registry {
   // keep this as a generic Codec, however the actual impl. returns the correct
   findMetaEvent (eventIndex: Uint8Array): Constructor<any>;
 
+  createType <K extends keyof InterfaceTypes> (type: K, ...params: any[]): InterfaceTypes[K];
   get <T extends Codec = Codec> (name: string, withUnknown?: boolean): Constructor<T> | undefined;
   getChainProperties (): ChainProperties | undefined;
   getDefinition (name: string): string | undefined;