update ledger message signing util

[m-aboelenein]

🔘 PR Type

What kind of change does this PR introduce?

• Enhancement

📜 Background

depends on secretkeylabs/xverse-core#364
to be tested with secretkeylabs/sats-connect-example#21

🔄 Changes

Enumerate the changes made in this pull request, detailing what has been modified, added, or removed. Include technical details and implications if necessary.

Impact:

• Explain the broader impact of these changes.
• How it improves performance, fixes bugs, adds functionality, etc.

🖼 Screenshot / 📹 Video

Include screenshots or a video demonstrating the changes. This is especially helpful for UI changes.

✅ Review checklist

Please ensure the following are true before merging:

• Code Style is consistent with the project guidelines.
• Code is readable and well-commented.
• No unnecessary or debugging code has been added.
• Security considerations have been taken into account.
• The change has been manually tested and works as expected.
• Breaking changes and their impacts have been considered and documented.
• Code does not introduce new technical debt or issues.

[github-actions]

Test with build here: https://github.com/secretkeylabs/xverse-web-extension/actions/runs/7756771596