Fix Ledger typed data signing uppercase 0X

The Ledger-specific signing screen showed the domain and message hashes
with a startin 0X due to an aggressive toUpperCase call. To make it
easier to scan, it now starts with 0x (lowercase x) as expected.

ui/components/Signing/Signer/SignerLedger/SignerLedgerSigning/index.tsx

@@ -56,13 +56,21 @@ function SignerLedgerSigningTypedData({
  typedData: EIP712TypedData
 }): ReactElement {
  const { EIP712Domain: _, ...typesForSigning } = typedData.types
- const domainHash = _TypedDataEncoder
+
+ // Below, we prefix the 0x so that we can uppercase the hex characters
+ // without uppercasing the X. This is because the Ledger displays hex
+ // characters all uppercase for this operation, but an uppercased X
+ // both makes our display and the Ledger's less accurate and makes it
+ // harder to scan the values.
+ const domainHash = `0x${_TypedDataEncoder
  .hashDomain(typedData.domain)
- .toUpperCase()
- const messageHash = _TypedDataEncoder
+ .substring(2)
+ .toUpperCase()}`
+ const messageHash = `0x${_TypedDataEncoder
  .from(typesForSigning)
  .hash(typedData.message)
- .toUpperCase()
+ .substring(2)
+ .toUpperCase()}`
 
  return (
  <TransactionDetailContainer>