[iOS] Auto Resize chrome icons on iOS to make it more consistent with other platforms - Toolbar items

[kubaflo]

Description

As shown in the screenshots, the image width is not being adjusted correctly, which results in only one toolbar item being scaled properly. To ensure consistent appearance across all items, I believe we should apply the same approach we used for TabBar icons and custom flyout/back icon to handle image sizing here as well.

<Shell.ToolbarItems>
    <ToolbarItem IconImageSource="groceries.png"/>
    <ToolbarItem IconImageSource="dotnet_bot.png"/>
</Shell.ToolbarItems>