Allow disabling the macos notch avoiding system

[Hackder]

Is your feature request related to a problem? Please describe.
When entering a non-native fullscreen on a macbook with a notch, wezterm attempts to avoid the notch.
I use my tabs at the bottom, and I want wezterm to render under the notch, instead of having a black bar at the top.
As far as I know there, is no way to disable the notch-avoidance system.

Describe the solution you'd like
Leaving the decision to the user would be the best option in my opinion. Having options like window_padding.
Let's say:
window_margin
get_os_recommended_padding

This would allow people to do all the possible options.

1. Leaving it with (0, 0, 0, 0) - what I want
2. window_margin = { top = get_os_recommended_padding().top ... - having a black bar at the top (the current)
3. window_padding = { top = get_os_recommended_padding().top ... - terminal background overlaps notch, but the content doesn't

Describe alternatives you've considered
Adding more options like disable_notch_avoidance would defeat the purpose of having a Turing complete language for configuration. Having these API's exposed to the user would also allow for workarounds for the non perfect notch avoidance (as it is currently).
Providing the primitives and letting the user choose, (with sane defaults) is usually the best with these kinds of tools.

Additional context
These images contain the two (my, and the current) behaviors.

NOTE: The current one is bugged and doesn't avoid the notch completely, see #3807 but this is unrelated to this feature request