Description of the new feature/enhancement

After #8459, we'll have the following scroll actions:

• scrollUp
• scrollDown
• scrollUpPage
• scrollDownPage
• scrollToTop
• scrollToBottom

This seems to be a case of us introducing new actions when we should be introducing new arguments instead. I propose the following designs:

Design 1: 3 args

• action: scroll
• arguments:
  • direction: up|down
  • mode: system|page|buffer
  • rowsToScroll: <optional int>

Personally dislike that rowsToScroll only works if you're in "system" mode. But it avoids the override in Design 2.

Design 2: Override mode

• action: scroll
• arguments:
  • direction: up|down
  • mode: system|page|buffer|<int>

This is basically Design 1, except rowsToScroll is embedded inside mode. If we go with this approach, maybe mode should be renamed to something like "amount"?

Open to discussion. Go!