Add option to toggle the title bar

[xipeng-jin]

Closes #5120

Summary

Add a option in settings "title_bar": { "show": true } to configure whether or not to show the title bar in the editor. Also add the action zed::ToggleTitleBar to toggle the current display state of the title bar.

Description

The previous PR #37428 got reverted because of macOS traffic lights issue was outstanding and there are new plans around redesign the title bar which makes it a must need from Zed team.

First, the macOS traffic light issue has been fixed in this PR which means they will be hidden/displayed with the state of title bar. Second, I believe the title bar is an essential to show when you are using collaboration features even for now. But on the other hand those features are never turned on for the solo mode or even offline mode. Therefore I think the better way is to have the Action with shortcut/keybinding to trigger toggling the title bar in the runtime. People can turn it on/off as needed. In the Zen mode, this feature enabling to hide title bar is also essential to achieve the minimal UI layout. I simplify the title bar setting tittle_bar.show with only containing two states true/false to minimize the complexity.

This PR will also part of addressing the problem in the issue #5066.

Here is a short demo

toggle.title.bar.demo.mov

Release Notes:

• Added two states true/false for configuring whether or not to show the title bar in the editor with setting title_bar.show.
• For macOS compatibility, added the functionality for hiding macOS specific traffic light when hiding the title bar. The traffic light will be toggled with the title bar.
• Added a zed action zed::ToggleTitleBar to toggling the state (show/hide) of title bar in runtime.

[maxdeviant]

Thank you for the PR, but we're not currently accepting any PRs to hide the title bar.

As stated in #38756:

we're preparing for the redesign which requires the toolbar being present.

[xipeng-jin]

Thank you @maxdeviant for your clarification.