Shell tab algnment as it is made for TabbedPage

[AncientLust]

Description

Currently Shell tabs are aligned to the left side, while TabbedPage allocates them for all available horizontal space.

Current alignment:

Alighment with a new API:

Public API Changes

<Shell
    x:Class= ...
    xmlns= ...
    Shell.TitleColor= ...
    Shell.TabAlignement="Fill"> // Fill, Start, End
</Shell>

Intended Use-Case

A way to control UI design without wasting time for dancing with custom renderers for each platform.