Enable @typescript-eslint/explicit-function-return-type in /src (#9788)

* Enable `@typescript-eslint/explicit-member-accessibility` on /src

* Prettier

* Enable `@typescript-eslint/explicit-function-return-type` in /src

* Fix types

* tsc strict fixes

* Delint

* Fix test

* Fix bad merge

src/actions/actionCreators.ts

@@ -15,7 +15,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { AsyncActionPayload } from "../dispatcher/payloads";
+import { AsyncActionFn, AsyncActionPayload } from "../dispatcher/payloads";
 
 /**
  * Create an action thunk that will dispatch actions indicating the current
@@ -45,7 +45,7 @@ import { AsyncActionPayload } from "../dispatcher/payloads";
  *                     `fn`.
  */
 export function asyncAction(id: string, fn: () => Promise<any>, pendingFn: () => any | null): AsyncActionPayload {
-    const helper = (dispatch) => {
+    const helper: AsyncActionFn = (dispatch) => {
         dispatch({
             action: id + ".pending",
             request: typeof pendingFn === "function" ? pendingFn() : undefined,

src/actions/handlers/viewUserDeviceSettings.ts

@@ -22,7 +22,7 @@ import defaultDispatcher from "../../dispatcher/dispatcher";
  * Redirect to the correct device manager section
  * Based on the labs setting
  */
-export const viewUserDeviceSettings = (isNewDeviceManagerEnabled: boolean) => {
+export const viewUserDeviceSettings = (isNewDeviceManagerEnabled: boolean): void => {
     defaultDispatcher.dispatch({
         action: Action.ViewUserSettings,
         initialTabId: isNewDeviceManagerEnabled ? UserTab.SessionManager : UserTab.Security,