[Skia] Pivot completely scrolls when using the mouse wheel

[jeromelaban]

Originally posted by @NicoAICP in https://github.com/unoplatform/uno/discussions/9032

If i use a Pivot item from the WinUI 2 stuff, i always get the issue in Skia.GTK (not in UWP) that if i scroll while having a pivot element close to me, it scrolls away the pivot element (as if i had an big webpage that i could scroll left and right, and i scroll away from the pivot)

Repro

   <Pivot Title="Pivot Control Sample">
        <Pivot.Items>
            <PivotItem Header="Pivot Item 1">
                <Grid>
                    <TextBlock Text="Item 1 Content" />
                </Grid>
            </PivotItem>
            <PivotItem Header="Pivot Item 2">
                <StackPanel>
                    <TextBlock Text="Item 2 Content" />
                    <TextBlock Text="http://windowsapptutorials.wordpress.com/"
                               FontStyle="Italic"
                               Foreground="#FF2975D1"></TextBlock>
                </StackPanel>
            </PivotItem>
        </Pivot.Items>
    </Pivot>

[ramezgerges]

It seems like we have a bunch of problems with Pivots:

• Scrolling up and down shouldn't scroll the Pivot sideways. I found an easy fix for this.
• It seems like we have a singular ScrollContentPresenter that does the scrolling for the headers and the content at the same time. On Windows, both the header Grid and the content itself both get scrolled (like uno), but the header Grid is scrolled a lot more slowly, such that when the entire content is scrolled, the header grid is only scrolled by one item title.
• Also, the content for the next pivot item starts scrolling into the view port to replace the previous pivot item. We don't seem to do this.
• Once the scrolling is released, it snaps to either the previous or the new pivot item depending on whether the scrolling made it past 50%.
• We also don't seem to have the < and > buttons on the side like this:

[MartinZikmund]

I think overall it would be worth porting the full control as there is a big number of backlog items for Pivot