Need good user experience for Rebond unlocks

[frankli-dev]

Here are the steps to reproduce.

I have two Unbonding chunks.

1. 100 unlocked
2. 30 unbonding

Then I click Rebond button for 100 unlocked chunk.

Once the extrinsic is finished, I see 30 unlocked chunk and 0 unbonding chunk.

Of course this is what staking pallet does. https://github.com/gluwa/polkadot-sdk/blob/release-polkadot-v1.1.0-patch/substrate/frame/staking/src/lib.rs#L512

So there is no on-chain/logic issue. Just the UI does not handle this as good user experience.

Users are thinking that they rebond the selected chunk. But actually, it rebonds from the last unbonding chunks.

rebond-unlock.mov

UI suggestion:
First, we should remove rebond button for chunks. Instead we can let users input amount of rebonds.
Or we can disable all unlocked chunks' rebond buttons until there are unbonding chunks.