P8/suspend resume validator

[soerenbf]

Purpose

Support changing the suspension status of validators.

Testing this requires a ledger application which supports the updated configure validator transaction (found here)

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.