[Feature Request] Different mouse sensitivity for each axis (for mousekeys feature)

Feature Request Type

• Core functionality
• Add-on hardware support (eg. audio, RGB, OLED screen, etc.)
• Alteration (enhancement/optimization) of existing feature(s)
• New behavior

Description

I am facing issue where the sensitivity of the y axis (up/down motion) is too sensitive, whereas the x axis movement is on the perfect speed.

The proposed solution is to add the MOUSEKEY_SENS_X and MOUSEKEY_SENS_Y to configure each axis sensitivity. It is done by multiplying the movement result, for example on the quantum/mousekey.c on mousekey_task() function with the default acceleration,

    if ((tmpmr.x || tmpmr.y) && timer_elapsed(last_timer_c) > (mousekey_repeat ? mk_interval : mk_delay * 10)) {
        if (mousekey_repeat != UINT8_MAX) mousekey_repeat++;
        if (tmpmr.x != 0) mouse_report.x = move_unit() * ((tmpmr.x > 0) ? 1 : -1) * MOUSEKEY_SENS_X;
        if (tmpmr.y != 0) mouse_report.y = move_unit() * ((tmpmr.y > 0) ? 1 : -1) * MOUSEKEY_SENS_Y;

        /* diagonal move [1/sqrt(2)] */
        if (mouse_report.x && mouse_report.y) {
            mouse_report.x = times_inv_sqrt2(mouse_report.x) * MOUSEKEY_SENS_X;
            if (mouse_report.x == 0) {
                mouse_report.x = 1;
            }
            mouse_report.y = times_inv_sqrt2(mouse_report.y * MOUSEKEY_SENS_Y);
            if (mouse_report.y == 0) {
                mouse_report.y = 1;
            }
        }
    }

So, for the example above, we let the MOUSEKEY_SENS_X be default 1.0 (because it is perfect already), and the MOUSEKEY_SENS_Y be 0.9 (because i need it a little less sensitive).

I already having the working code on my repo.. is it okay if i open a PR? thanks