Fixed Shell Navigating event issue when switching tabs

[Vignesh-SF3580]

Issue Detail

Mac and iOS: Clicking on an already-selected tab triggered the Navigating event unnecessarily. Windows: The Navigating event was not triggered when switching tabs.

Root Cause

Mac and iOS: The event was triggered without checking if the tab was already selected. Windows: There was no code in place to trigger the Navigating event upon tab switches.

Description of Change

Mac and iOS: Modified the code to trigger Navigating only if a new tab is selected. Windows: Added logic to trigger Navigating when switching to a different tab.

Tested the behaviour in the following platforms

• [x] Android
• [x] Windows
• [x] iOS
• [x] Mac

Issues Fixed

Fixes https://github.com/dotnet/maui/issues/25599

Screenshots

Before Issue Fix	After Issue Fix

[dotnet-policy-service[bot]]

Hey there @Vignesh-SF3580! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[jsuarezruiz]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 3 pipeline(s).

[jsuarezruiz]

/azp run

[rmarinho]

/rebase

[rmarinho]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 3 pipeline(s).

[jsuarezruiz]

/azp run