Passkey: check account signature on passkey

[saraswatpuneet]

Go after #2037

Goal

The goal of this PR is to setup functions and tests for account signature checks

Part of: #2028

Checklist

• [ ] Chain spec updated
• [ ] Custom RPC OR Runtime API added/changed? Updated js/api-augment.
• [ ] Design doc(s) updated
• [x] Tests added
• [ ] Benchmarks added
• [ ] Weights updated

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 86.36364% with 3 lines in your changes missing coverage. Please review.

Files	Coverage Δ
pallets/passkey/src/lib.rs	69.23% <86.36%> (+15.65%)	:arrow_up: