New functionality: Swipe between pages

[ayakut16]

Added this new functionality requested in #5 which I think is quite useful. The functionality backed by native TabView component with .tabViewStyle(.page) which is only available after iOS 14, thus I updated the availability.

Also the pages do not have to be separate components now, they can be passed as we do in TabView, e.g:

SlidingTabView(selection: self.$selectedTabIndex, tabs: ["First", "Second"]) {
    Text("First View")
    Text("Second View")
}

Note that this change is not backward compatible so I believe increasing the version to 2.0 is necessary.

In the first commit removed @State and used the @Binding property instead this also Fixes #7 and Fixes #10.

Fixes #5

https://user-images.githubusercontent.com/9766788/215855151-8d50381c-57da-402a-832c-81f63da578c1.mov

[ayakut16]

This repo seems to be abandoned, I forked it and added this feature: https://github.com/ayakut16/SlidingTabView

If this ever comes back to life again, please let me know, I'd be happy to continue here.