Refactor - crypto

[DaMatrix]

Description

This PR depends on #42 (placeholders) and #43 (serialize-utils).

This PR refactors the structs in the crypto module to consistently implement all the same traits, serialize to hex strings human-readable formats (while still supporting the old human-readable format), serialize efficiently for binary formats, and implement Placeholder+PlaceholderSeed.

Changelog

• Replaced all structs under crypto which represent a fixed-length byte array with a macro
  • This macro handles serialization, display, parsing, serialization, and placeholder value generation
• Made keypair generation actually panic in the face of impossible errors, rather than logging a warning and returning an invalid keypair

Type of Change

Please mark the appropriate option by putting an "x" inside the brackets:

• Bug fix
• New feature
• Enhancement or optimization
• Documentation update
• Other (please specify)

Checklist

Put an "x" in the boxes that apply. If you're unsure about any of these, don't hesitate to ask. We're here to help!

• I have tested the changes locally and they work as expected.
• I have added necessary documentation or updated existing documentation.
• My code follows the project's coding standards and style guidelines.
• I have added/updated relevant tests to ensure the changes are properly covered.
• I have checked for and resolved any merge conflicts.
• My commits have clear and descriptive messages.

Screenshots (if applicable)

If the changes affect the UI or have visual effects, please provide screenshots or GIFs showcasing the changes.

Additional Context (if applicable)

Add any additional context or information about the changes that may be helpful in understanding the pull request.

Related Issues (if applicable)

If this pull request is related to any existing issues, please list them here.

Requested Reviewers

Mention any specific individuals or teams you would like to request a review from.

[BHouwens]

Nice quality of life updates here @DaMatrix. Consistency improvements are always a winner