Move api-derive to correct location (#4343)

* Move api-derive to correct location

* Adjust (linting ok)

* No composite

* ApiDerive split

* Adjust

* Still WIP, getting closer

* It lints

* derive build issues sorted

* It builds :)

* Add system_health to mock

* api-augment usage

* Cleanups

* Adjust paths

* linting

* Some <'s

* Revert <>'s

* linting

* ordering

* Augmentation tweaks

* yarn.lock

* export

packages/api-derive/src/staking/stakerPrefs.ts

@@ -0,0 +1,27 @@
+// Copyright 2017-2021 @polkadot/api-derive authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import type { Observable } from 'rxjs';
+import type { EraIndex } from '@polkadot/types/interfaces';
+import type { DeriveApi, DeriveStakerPrefs } from '../types';
+
+import { map } from 'rxjs';
+
+import { memo } from '../util';
+import { erasHistoricApplyAccount } from './util';
+
+export function _stakerPrefs (instanceId: string, api: DeriveApi): (accountId: Uint8Array | string, eras: EraIndex[], withActive: boolean) => Observable<DeriveStakerPrefs[]> {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  return memo(instanceId, (accountId: Uint8Array | string, eras: EraIndex[], _withActive: boolean): Observable<DeriveStakerPrefs[]> =>
+    api.query.staking.erasValidatorPrefs.multi(eras.map((e) => [e, accountId])).pipe(
+      map((all): DeriveStakerPrefs[] =>
+        all.map((validatorPrefs, index): DeriveStakerPrefs => ({
+          era: eras[index],
+          validatorPrefs
+        }))
+      )
+    )
+  );
+}
+
+export const stakerPrefs = erasHistoricApplyAccount('_stakerPrefs');