Added AlertDialog.inset_padding property

[all-mute]

Added AlertDialog.inset_paddin property to manage padding of Alert Dialog. On mobile phones with small width of screen, Dialog looks very thin. All pytests passed.

Usage example:
import flet as ft

def main(page: ft.Page):
page.title = "AlertDialog examples"

dlg = ft.AlertDialog(
    title=ft.Text("Hello, you!"), on_dismiss=lambda e: print("Dialog dismissed!"), inset_padding=ft.padding.symmetric(vertical=0, horizontal=0)
)

def close_dlg(e):
    dlg_modal.open = False
    page.update()

dlg_modal = ft.AlertDialog(
    modal=True,
    title=ft.Text("Please confirm"),
    content=ft.Text("Do you really want to delete all those files?"),
    actions=[
        ft.TextButton("Yes", on_click=close_dlg),
        ft.TextButton("No", on_click=close_dlg),
    ],
    actions_alignment=ft.MainAxisAlignment.END,
    on_dismiss=lambda e: print("Modal dialog dismissed!"),
)

def open_dlg(e):
    page.dialog = dlg
    dlg.open = True
    page.update()

def open_dlg_modal(e):
    page.dialog = dlg_modal
    dlg_modal.open = True
    page.update()

page.add(
    ft.ElevatedButton("Open dialog", on_click=open_dlg),
    ft.ElevatedButton("Open modal dialog", on_click=open_dlg_modal),
)

ft.app(target=main)

[CLAassistant]

All committers have signed the CLA.

[all-mute]

idk what happend here. I have never pull requested before, sorry if i missed something obvious)

consol log from appveyor:
Build started git clone -q --branch=main https://github.com/all-mute/flet_ad_inset.git /home/appveyor/projects/flet-ad-inset git checkout -qf e8874044798b3a01ee5d898[2](https://ci.appveyor.com/project/all-mute/flet-ad-inset/build/job/vgp9s9m98fqtmqc2#L2)[3](https://ci.appveyor.com/project/all-mute/flet-ad-inset/build/job/vgp9s9m98fqtmqc2#L3)5f99073e3dfb5[4](https://ci.appveyor.com/project/all-mute/flet-ad-inset/build/job/vgp9s9m98fqtmqc2#L4)3 Configuring 'stack' Enabling Python 3.10.12 Running "install" scripts if ($env:APPVEYOR_REPO_TAG_NAME) { $v = $env:APPVEYOR_REPO_TAG_NAME.replace("v", "") } else { $cv = [version](git describe --abbrev=0).substring(1) $v = "$($cv.major).$($cv.minor+1).0+$($env:APPVEYOR_BUILD_NUMBER)" } Update-AppveyorBuild -Version $v fatal: No names found, cannot describe anything. InvalidOperation: Line | 4 | $cv = [version](git describe --abbrev=0).substring(1) | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | You cannot call a method on a null-valued expression. Command exited with code 12[8](https://ci.appveyor.com/project/all-mute/flet-ad-inset/build/job/vgp9s9m98fqtmqc2#L8) Build failed

[FeodorFitsner]

Thanks for your PR!

See the error here: https://ci.appveyor.com/project/flet-dev/flet/builds/48173018/job/jxeql1n2x1h46xq1#L224
It's because AlertDialog.insetPadding expects non-nullable EdgeInsets while parseEdgeInsets() returns nullable EdgeInsets?.

Solution would be providing default value if parse function returns null:

insetPadding: parseEdgeInsets(widget.control, "insetPadding") ?? EdgeInsets.symmetric(horizontal: 40.0, vertical: 24.0),

Please fix.

[ndonkoHenri]

Dont forget to update the online docs too.