fix:ControlState should be resolved based on user-defined order

[ndonkoHenri]

Fixes #4409

Test Code

import flet as ft


def main(page: ft.Page):
    page.horizontal_alignment = ft.CrossAxisAlignment.CENTER
    page.vertical_alignment = ft.MainAxisAlignment.CENTER
    button = ft.TextButton(
        "Test Button",
        style=ft.ButtonStyle(
            bgcolor={
                ft.ControlState.DEFAULT: ft.colors.with_opacity(0.786, "ffffff"),
                 ft.ControlState.PRESSED: ft.colors.BLUE,
                ft.ControlState.HOVERED: ft.colors.GREEN,
            }
        ),
    )
    page.add(button)


ft.app(main)

Summary by Sourcery

Resolve ControlState based on user-defined order and replace the empty string with 'default' for default state handling.

Bug Fixes:

• Fix the resolution of ControlState to respect user-defined order, ensuring that the correct state is applied based on the specified sequence.

Enhancements:

• Deprecate the use of an empty string for default state and replace it with the term 'default' for clarity and consistency.

Tests:

• Update tests to reflect the change from an empty string to 'default' for default state handling, ensuring that the new logic is correctly validated.