Move (some) from session & elections to srml/types (#1158)

* Move (some) from session & elections to srml/types

* Just use createType instad of (new ClassOf(type))(value)

* Cleanup generation script (import file duplication)

packages/api-metadata/src/consts/fromMetadata/fromMetadata.spec.ts

@@ -4,7 +4,7 @@
 
 import { Metadata, BlockNumber } from '@polkadot/types';
 import json from '@polkadot/types/Metadata/v6/static';
-import { injectDefinitions } from '@polkadot/types/Metadata/util/testUtil';
+import { injectDefinitions } from '@polkadot/types/srml';
 
 import fromMetadata from '../fromMetadata';