Add AppBar.adaptive

[ndonkoHenri]

Test code:

import flet as ft


def main(page: ft.Page):
    page.theme_mode = "light"
    page.window_always_on_top = True

    page.appbar = ft.AppBar(
        title=ft.Text("Flet"),
        actions=[
            ft.IconButton(ft.icons.MENU),
            ft.IconButton(ft.icons.SEARCH),
        ],
        bgcolor=ft.colors.BLUE_ACCENT,
        adaptive=True,
    )

    page.add(
        ft.Text("Hello, Flet!", theme_style=ft.TextThemeStyle.HEADLINE_MEDIUM),
    )


ft.app(target=main)