feat(macos): Fix with_titlebar_transparent, add WindowExtMacOS::set_titlebar_transparent

[probablykasper]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

Used @JonasKruckenberg's code from tauri-apps/tauri#2663, and it looks like it works!

Fixes with_titlebar_transparent by setting a style mask, and adds WindowExtMacOS::set_titlebar_transparent

[JonasKruckenberg]

there is also with_titlebar_transparent already, which (I think?) was supposed to do this already, but doesn't. Maye we could just fix with_titlebar_transparent with this implementation? 🤔

[probablykasper]

there is also with_titlebar_transparent already, which (I think?) was supposed to do this already, but doesn't. Maye we could just fix with_titlebar_transparent with this implementation? 🤔

Ah, looks like you're right!

I made it so with_titlebar_transparent is what's used, and I also made it not hide the title because there's a separate option for that.

[amrbashir]

There is WindowBuilderExtMacOS::with_fullsize_content_view for exactly doing this. Users should just use it.

Suggested change

	let mut style_mask = ns_window.styleMask();
	style_mask.set(
	NSWindowStyleMask::NSFullSizeContentViewWindowMask,
	true,
	);
	ns_window.setStyleMask_(style_mask);

[amrbashir]

This shouldn't be the responsibility of this method, it should probably be split into another method WindowExtMacOS::set_fullsize_content_view

[amrbashir]

I don't think it was broken in the first place, because it seems like users needed to just pair it with WindowBuilderExtMacOS::with_fullsize_content_view in wry/tauri apps.

[probablykasper]

Alright, looks like tao already supports what would be needed for making titlebars transparent:
with_titlebar_transparent + with_fullsize_content_view + with_title_hidden