Report descriptive error message when migrations fail

Nobody has claimed this yet.

### Describe the bug

During a migration, when a user claims their stake, the pool calls the bonding manager to execute a transferBond. Due to [protocol safeguards](https://github.com/livepeer/protocol/blob/d03671e2e159bbc856feace83371876cf25124e3/contracts/bonding/BondingManager.sol#L695), this call will fail if the orchestrator the user originally staked to on L1 (now represented on L2) has not yet called `reward`. At present, this failure surfaces to users as a generic error, providing no indication of the underlying cause.

### To Reproduce

Currently hard to reproduce without us [launching a testnet](https://forum.livepeer.org/t/pre-proposal-protocol-r-d-special-purpose-entity/3160/6) unless you have an old wallet with unmigrated stake.

### Expected behavior

We should catch the [](https://github.com/livepeer/protocol/blob/d03671e2e159bbc856feace83371876cf25124e3/contracts/bonding/BondingManager.sol#L1729) error and explain this behavoir. "The migration currently failed since your orchestrator has not yet called rewards and doing the claim would cause the pool to lose out of inflation rewards. If the orchestrator stays inactive for to long you could use the [claimEarnings](https://github.com/livepeer/protocol/blob/d03671e2e159bbc856feace83371876cf25124e3/contracts/bonding/BondingManager.sol#L455) yourself on L2 to override this`.

### Screenshots

We should catch the [ILLEGAL_CLAIM_EARNINGS](https://github.com/livepeer/protocol/blob/d03671e2e159bbc856feace83371876cf25124e3/contracts/bonding/BondingManager.sol#L1729) error and surface a clear explanation to the user.

“The migration failed because your orchestrator has not yet called `reward`. Proceeding with the claim now would cause the pool to forgo inflationary rewards. If the orchestrator remains inactive for too long, you may manually call [`[claimEarnings](https://github.com/livepeer/protocol/blob/d03671e2e159bbc856feace83371876cf25124e3/contracts/bonding/BondingManager.sol#L455)`](https://github.com/livepeer/protocol/blob/d03671e2e159bbc856feace83371876cf25124e3/contracts/bonding/BondingManager.sol#L455) on L2 to override this.”

### Desktop OS

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### Desktop Browser

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### Desktop Wallet

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### Desktop App/Extension Version

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### Smartphone Device

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### Smartphone OS

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### Smartphone Browser

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### Smartphone Wallet

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### Smartphone App/Extension Version

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### Additional context

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Trace the migration claim flow and its handling of the BondingManager.sol ILLEGAL_CLAIM_EARNINGS error at the linked contract location. Surface the supplied explanation, including the reward prerequisite and the L2 claimEarnings override, and verify that this message appears when the migration claim fails.

Written by the indexing model from the issue text.