Fix: Update event indexer and txn indexer to insert txDigest as a hex string

[faisal-chainlink]

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[FelixFan1992]

should we consider what happens when err is not nil?

[FelixFan1992]

or we can safely assume that transactionRecord.Digest is going to be valid

[faisal-chainlink]

I think we can safely assume it is always there. The thing that I want to check is if the core node currently assumes this to be a base64 string when getting events, if that's the case, we need to make a small change in core as well. cc @stackman27

[FelixFan1992]

ok let's wait for his input

[stackman27]

Since both fields are expected as bytes, i think decoded hex is better

type Head struct {
	Height string
	Hash   []byte
	// Timestamp is in Unix time
	Timestamp uint64
}

type Sequence struct {
	// This way we can retrieve past/future sequences (EVM log events) very granularly, but still hide the chain detail.
	Cursor string
	TxHash []byte
	Head
	Data any
}