Remove restrictions from `prependMiddleware()` and `middleware()` methods

### Proposed new feature or change

Currently `middleware()`  can only be used only before an action is added, and `prependMiddleware()` only after action is added.

We can remove this restrictions:

- `middleware()` adds middleware to end of list if action haven't been added, and adds it before action otherwise.
- `prependMiddleware()` always prepends middleware to the list.