fix TabViewIndicator position on RTL

[Tarekka]

Description of Bug

TabView - TabViewIndicator goes off the screen when flow direction is RTL. This is caused by the UpdateTabIndicatorPosition method not taking RTL into consideration when calculating the position to translate the indicator to.

Issues Fixed

• Fixes [Bug] TabView - TabIndicator doesn't show when flow direction is RTL #1982

Behavioral Changes

PR Checklist

• Has a linked Issue, and the Issue has been approved
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard

• Updated documentation

[jfversluis]

Now that we're so close to the sunsetting of Xamarin (and therefore also Xamarin Community Toolkit) unfortunately we won't be able to take this in anymore, we're really sorry about that. Nevertheless, thank you so much for your time and effort that you have put into this PR, we really appreciate it.

Please have a look at the evolution of the Xamarin Community Toolkit, The .NET MAUI Community Toolkit. A lot of development has been going on there. Hopefully this issue was already fixed in that codebase. If not, feel free to port this over to there.

Again, thank you so much for being a contributor and Xamarin user!