[iOS] Disabled animation for NavigationBar on initial display

[kubaflo]

Description of Change

This PR disables the animation for showing or hiding the navigation bar when a page is displayed for the first time by setting Shell.NavBarIsVisible. Subsequent changes to Shell.NavBarIsVisible remain unaffected and will animate (maybe they shouldn't though? On Android, displaying or hiding the navigation bar does not involve any navigation transitions)

Issues Fixed

Fixes #26994

Before	After
Screen.Recording.2025-01-12.at.02.51.47.mov	Screen.Recording.2025-01-12.at.02.45.59.mov

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[jsuarezruiz]

@PureWeen Thoughts?

[PureWeen]

Description of Change

This PR disables the animation for showing or hiding the navigation bar when a page is displayed for the first time by setting Shell.NavBarIsVisible. Subsequent changes to Shell.NavBarIsVisible remain unaffected and will animate (maybe they shouldn't though? On Android, displaying or hiding the navigation bar does not involve any navigation transitions)

Issues Fixed

Fixes #26994

Before After
Screen.Recording.2025-01-12.at.02.51.47.mov
Screen.Recording.2025-01-12.at.02.45.59.mov

Can you post your sample that you're reproing here?

I'm having a little trouble mapping your description to the issue the user has logged.
Also, the action you're taking in the two videos is different

[kubaflo]

Description of Change

This PR disables the animation for showing or hiding the navigation bar when a page is displayed for the first time by setting Shell.NavBarIsVisible. Subsequent changes to Shell.NavBarIsVisible remain unaffected and will animate (maybe they shouldn't though? On Android, displaying or hiding the navigation bar does not involve any navigation transitions)

Issues Fixed

Fixes #26994
Before After
Screen.Recording.2025-01-12.at.02.51.47.mov
Screen.Recording.2025-01-12.at.02.45.59.mov

Can you post your sample that you're reproing here?

I'm having a little trouble mapping your description to the issue the user has logged. Also, the action you're taking in the two videos is different

<Shell
    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    x:Class="Maui.Controls.Sample.SandboxShell"
    Background="Red"
    Shell.ForegroundColor="White"
    xmlns:local="clr-namespace:Maui.Controls.Sample"
    x:Name="shell">
    <TabBar>
        <Tab Title="MainPage1">
            <ContentPage
                Background="Green"
                Title="Page1"/>
        </Tab>
        <Tab Title="MainPage1">
            <ShellContent Title="wwa"
                          Route="wwa">
                <ShellContent.ContentTemplate>
                    <DataTemplate>
                        <ContentPage Background="Red"
                                     Shell.NavBarIsVisible="False"
                                     Title="Page1"/>
                    </DataTemplate>
                </ShellContent.ContentTemplate>
            </ShellContent>
        </Tab>
    </TabBar>
</Shell>

Screen.Recording.2025-01-17.at.00.34.29.mov