Add support for EIP-712 typed hash signatures for non-legacy devices

[mdehoog]

Fixes #5294, please see that issue for a more detailed rationale for this PR.

#1835 added support for signing EIP-712 data payloads for Trezor T, but without support for signing EIP-712 data hashes.
#1970 added support for signing EIP-712 hashes for legacy Trezors, but not for newer models.

This PR adds support for signing data hashes to newer devices. This is useful for signing EIP-712 hashes directly, for example for (Gnosis) Safe signatures.

Context: we maintain https://github.com/base/eip712sign for signing typed hashes with hardware devices. We recently started work on adding Trezor support (see base/eip712sign#19).

[mdehoog]

could alternatively remove this and just reuse ethereum__title_confirm_typed_data

[matejcik]

This is useful for signing EIP-712 hashes where the data / domain cannot be customized, like for (Gnosis) Safe signatures.

i have no idea what that means. how can you not customize data/domain in an EIP712 payload?

This PR adds support for signing data hashes to newer devices.

absent a very good rationale, we don't want to introduce blind-signing unknown EIP712 payloads

[mdehoog]

@matejcik thanks very much for your reply... and apologies for not including a good rationale. I've opened #5294 which explains our use case better.

This is useful for signing EIP-712 hashes where the data / domain cannot be customized, like for (Gnosis) Safe signatures.

i have no idea what that means. how can you not customize data/domain in an EIP712 payload?

I incorrectly assumed we couldn't send domain separators that were compatible with Safe's transaction hash using the existing typed data struct messages; please ignore this comment (I've removed it from the PR text).

[mdehoog]

Replaced by #5344