Feature changes

• Fix issue in tick scheduling of the countdowns
• Added configurable refresh speed for the displays

display:
  refresh:
    # How often the bossbar progress bar and title are refreshed, in ticks (20 ticks = 1 second).
    # Lower values produce smoother animation. Minimum is 1.
    bossbar-ticks: 1
    # How often the scoreboard sidebar is refreshed, in ticks. Minimum is 1.
    scoreboard-ticks: 1

Code structure changes

• Added MessageBatch structure to keep more clarity in 1 countdown with multiple displays being 1 "batch"
• Added DisplayMessage that represents 1 message for 1 display