Deprecates `RewardDestination::Controller` variant.

- [x] `RewardDestination::Controller` annotated with `#[deprecated]`.
- [x] `Controller` variant is now handled the same way as `Stash` in
`payout_stakers`.
- [x] `set_payee` errors if `RewardDestination::Controller` is provided.
- [x] Added `update_payee` call to lazily migrate
`RewardDestination::Controller` `Payee` storage entries to
`RewardDestination::Account(controller)` .
- [x] `payout_stakers_dead_controller` has been removed from benches &
weights - was not used.
- [x] Tests no longer use `RewardDestination::Controller`.

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Co-authored-by: command-bot <>
Co-authored-by: Gonçalo Pestana <[email protected]>
Co-authored-by: georgepisaltu <[email protected]>