add more window actions

[n1ght-hunter]

users should be able to with window::Actions:

• toggle decorations live
• toggle always on top i.e. for pinning a window
• change icon live to show changes in app state etc

There may be a better way to handle the type for the Icon enum but you cant import winit into iced_native due to cyclic package dependency's. feel free to say a better way then i have done.

Also what do people think the Action::Fullscreen should do? currently it full screens on primary monitor but IMO i think it should full screen on current monitor.

And should it be an option to full screen exclusive. currently you can only full screen windowed borderless

[n1ght-hunter]

@tarkah I'm trying to add

iced/src/window/icon.rs

Lines 28 to 33 in b4aedce

	#[cfg(feature = "image_rs")]
	pub fn from_file<P: AsRef<Path>>(icon_path: P) -> Result<Self, Error> {
	let icon = image_rs::io::Reader::open(icon_path)?.decode()?.to_rgba8();
	Self::from_rgba(icon.to_vec(), icon.width(), icon.height())
	}

iced/src/window/icon.rs

Lines 40 to 56 in b4aedce

	pub fn from_file_data(
	data: &[u8],
	explicit_format: Option<image_rs::ImageFormat>,
	) -> Result<Self, Error> {
	let mut icon = image_rs::io::Reader::new(std::io::Cursor::new(data));
	let icon_with_format = match explicit_format {
	Some(format) => {
	icon.set_format(format);
	icon
	}
	None => icon.with_guessed_format()?,
	};
	let pixels = icon_with_format.decode()?.to_rgba8();
	Self::from_rgba(pixels.to_vec(), pixels.width(), pixels.height())
	}

to the my iced native icon https://github.com/Night-Hunter-NF/iced/blob/master/native/src/window/icon.rs
but iced_native doesn't have image as a dep.
just wondering what you thoughts are on this

[hecrj]

I feel we are tackling multiple use cases here and some of the actions seem quite straightforward while some others may need further discussion.

Since there is not an RFC for these changes, I feel we should at least split this PR into smaller ones; one for each new action.

[n1ght-hunter]

ok yup will work on splitting them up into different PRs

[n1ght-hunter]

split into prs above