Swift rewrite

[Bright-Shard]

A rewrite of all the Swift code, which minimises calls to NSApp.sendEvent (a method which causes random hangs/pauses while we're trying to handle events).

Bugs

• The stoplight buttons on the window aren't coloured right on hover. I can't figure out a way to get just the icon to appear, without changing the background.
• The hit targets for resizing the window might not be the right size. I'm having to manually program window resizes, so I don't know what they normally are sized at, and went for ~7px.
• The mouse cursor doesn't always reset correctly to the arrow cursor after resizing the window. As far as I can tell, this is an issue with NSCursor (like a race condition from setting the cursor twice or something), not my code, but it's still an issue.
• Not all events currently implemented.
• (As noted by Spey) Sometimes the cursor changes to a resize cursor, but dragging doesn't actually resize the window
• macOS doesn't differentiate middle mouse clicks from other mouse buttons. Need to figure out what button number represents the middle mouse button, and use that for middle mouse events.

[Bright-Shard]

Features to implement:

• Window initialization
• Multiple windows
• OpenGL support
• Metal support
• Window deco
• Window resizing events
• Window resize increments
• Window transparency
• Window max/min-imisation
• Fullscreen
• Exclusive Fullscreen
• HiDPI (All macs are HiDPI, should work out of the box)
• Popups
• Monitor info
• Video mode query
• Mouse events
• Set, lock, or confine mouse cursor
• Custom cursor icon
• Cursor hittests
• Touch events
• Touch pressure
• Multitouch
• Keyboard events
• Drag 'n drop
• Raw device events
• Gamepad/joystick events
• Device movement events

Taken from https://github.com/loki-chat/lokinit/blob/main/FEATURES.md

Events to support:

• Window resized
• Window moved
• Window close requested
• Window destroyed
• Redraw requested
• Focus in
• Focus out
• File dropped
• File hovered
• File hover cancelled
• Keyboard events:
  • Key press
  • Key release
  • Key repeat
  • IME commit
• Mouse events:
  • Pressed
    • Left
    • Middle
    • Right
    • Other
  • Released
    • Left
    • Middle
    • Right
    • Other
  • Moved
  • Entered window
  • Left window
  • Scroll wheel
• Touch events:
  • Started
  • Moved
  • Ended
  • Cancelled

Taken from EventType enum.

[Speykious]

I discovered another bug: while resizing, move the cursor very fast to try to shrink the window to 0. The window disappears and never reappears again.

[Bright-Shard]

Source for mouse button numbers:
https://github.com/rust-windowing/winit/blob/81fd39485f81bb3345786f86e387bd3aac925d84/src/platform_impl/macos/view.rs#L1032-L1047

[Bright-Shard]

Source for keycodes: https://developer.mozilla.org/en-US/docs/web/api/ui_events/keyboard_event_code_values#code_values_on_mac

This may be useable for other platforms as well.

[Bright-Shard]

Moved progress tracking to #3