Add a new icon for Scroll speed setting

[ihhub]

Preliminary checks

• [X] I've checked that there aren't other open issues on the same topic.

Describe the problem requiring a solution

We utilize many existing icons and this is bad. Every option should have its own unique icon. Scroll speed option uses the same set of icons as monster speed in battle:

Describe the possible solution

Add a set of brand new icons which is suitable for this option.

Additional info

No response

[ihhub]

I assigned this issue for myself but in reality it is handled by @golden-lining