Hercules Inpulse 200 - Configure shift-browser knob to scroll the library (quick)

[nlw0]

Shift-browser knob is currently unassigned. This assigns it to scroll the library (page up/down) instead of just moving the cursor, so you can move more quickly in a large library.

[ronso0]

Thank you for this PR, code LGTM!
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Mapping changes go to the current stable branch (2.4), I've changed the base branch here accordingly. Please rebase your local branch and force-push.

Please also update the manual page https://github.com/mixxxdj/manual/blob/2.4/source/hardware/controllers/hercules_djcontrol_inpulse_200.rst

[nlw0]

All right. I rebased this PR and created one for the documentation mixxxdj/manual#626

[ronso0]

just waiting for the manual PR, if you like to polish it (AutoDJ hint) I'll merge afterwards. If not let me know.

[ronso0]

Thanks!