Log when a round is advanced.

[td202]

Purpose

Closes #975

This produces log messages each time the round is advanced, either by a QC or a TC. For example:

2023-08-18T14:52:41.622048500+02:00 DEBUG: Konsensus: Advancing round: round 34 timed out.
2023-08-18T14:52:41.828110800+02:00 DEBUG: Konsensus: Advancing round: round 35 certified block 2d8eede2e8fc749d6da21f3e9e875fdc4b6339668dfb48f47d7a497d24976be5

Changes

• Add debug-level logging to advanceRoundWithTimeout.
• Add debug-level logging to advanceRoundWithQuorum.

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.