Allow control how many lines to scroll at once using the mouse wheel

[DexerBR]

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Currently vertical scrolling is limited to one line per scroll, and does not have an exposed option to control it. This PR allows you to scroll more than one line using a mouse wheel. The number of rows scrolled at a time will default to 3.

Maintainer merge checklist

• [x] Title is descriptive/clear for inclusion in release notes.
• [x] Applied a Component: xxx label.
• [ ] Applied the api-deprecation or api-break label.
• [ ] Applied the release-highlight label to be highlighted in release notes.
• [ ] Added to the milestone version it was merged into.
• [ ] Unittests are included in PR.
• [x] Properly documented, including versionadded, versionchanged as needed.

[tshirtman]

#7615 was merged :)

[DexerBR]

I changed the number of lines that scroll by default to 3, as it is more convenient, but this can be discussed.

[misl6]

@DexerBR can you take care of the failing tests?

[DexerBR]

@misl6 Tests have been fixed!

[DexerBR]

Hi @misl6 ! Is there anything else that needs to be addressed before merging this one?