improve: Add appliedRelayerFeePct to FillRelay event

[nicholaspai]

Emitting both the original and the updated relayerFeePct allows off-chain clients to distinguish between correctly and incorrectly sped up fillRelay calls with updated relayer fee %'s. Currently, the client has no way to determine if a FillRelay event emitted by a speed up relay (i.e. calling fillRelayWithUpdatedFee) was a valid fill or not.

The current exploit would be to call fillRelay for a deposit with ALL of the correct params except for relayerFeePct, which the attacker would set to something lower than expected like 0. Clients would not be able to easily detect if this modified relayerFeePct=0 came from a correct fillRelayWithUpdatedFee call.

[nicholaspai]

I removed this to get around a stack too deep error but also realized we don't use relayHash in the current client code so its a reasonable delete

[nicholaspai]

Note, this PR will require changing the Fill object interface in relayer-v2/interfaces/SpokePool and adding a test that valid speed up fills are included in fillsToRefund while invalid fill calls with all matching params except for the relayerFeePct are ignored.