Overhaul the Keyboard API

Overhaul the keyboard API in winit to mimic the W3C specification
to achieve better crossplatform parity. The `KeyboardInput` event
is now uses `KeyEvent` which consists of:

  - `physical_key` - a cross platform way to refer to scancodes;
  - `logical_key`  - keysym value, which shows your key respecting the
                     layout;
  - `text`         - the text produced by this keypress;
  - `location`     - the location of the key on the keyboard;
  - `repeat`       - whether the key was produced by the repeat.

And also a `platform_specific` field which encapsulates extra
information on desktop platforms, like key without modifiers
and text with all modifiers.

The `Modifiers` were also slightly reworked as in, the information
whether the left or right modifier is pressed is now also exposed
on platforms where it could be queried reliably. The support was
also added for the web and orbital platforms finishing the API
change.

This change made the `OptionAsAlt` API on macOS redundant thus it
was removed all together.

Co-authored-by: Artúr Kovács <kovacs.artur.barnabas@gmail.com>
Co-authored-by: Kirill Chibisov <contact@kchibisov.com>
Co-authored-by: daxpedda <daxpedda@gmail.com>
Fixes: #2631.
Fixes: #2055.
Fixes: #2032.
Fixes: #1904.
Fixes: #1810.
Fixes: #1700.
Fixes: #1443.
Fixes: #1343.
Fixes: #1208.
Fixes: #1151.
Fixes: #812.
Fixes: #600.
Fixes: #361.
Fixes: #343.

src/platform_impl/macos/appkit/event.rs

@@ -67,35 +67,6 @@ extern_methods!(
             }
         }
 
-        pub fn keyEventWithType(
-            type_: NSEventType,
-            location: NSPoint,
-            modifier_flags: NSEventModifierFlags,
-            timestamp: NSTimeInterval,
-            window_num: NSInteger,
-            context: Option<&NSObject>,
-            characters: &NSString,
-            characters_ignoring_modifiers: &NSString,
-            is_a_repeat: bool,
-            scancode: c_ushort,
-        ) -> Id<Self, Shared> {
-            unsafe {
-                msg_send_id![
-                    Self::class(),
-                    keyEventWithType: type_,
-                    location: location,
-                    modifierFlags: modifier_flags,
-                    timestamp: timestamp,
-                    windowNumber: window_num,
-                    context: context,
-                    characters: characters,
-                    charactersIgnoringModifiers: characters_ignoring_modifiers,
-                    isARepeat: is_a_repeat,
-                    keyCode: scancode,
-                ]
-            }
-        }
-
         #[sel(locationInWindow)]
         pub fn locationInWindow(&self) -> NSPoint;
 
@@ -109,12 +80,8 @@ extern_methods!(
         #[sel(type)]
         pub fn type_(&self) -> NSEventType;
 
-        // In AppKit, `keyCode` refers to the position (scancode) of a key rather than its character,
-        // and there is no easy way to navtively retrieve the layout-dependent character.
-        // In winit, we use keycode to refer to the key's character, and so this function aligns
-        // AppKit's terminology with ours.
         #[sel(keyCode)]
-        pub fn scancode(&self) -> c_ushort;
+        pub fn key_code(&self) -> c_ushort;
 
         #[sel(magnification)]
         pub fn magnification(&self) -> CGFloat;
@@ -169,6 +136,26 @@ extern_methods!(
             unsafe { msg_send_id![self, charactersIgnoringModifiers] }
         }
 
+        pub fn lshift_pressed(&self) -> bool {
+            let raw_modifiers = self.modifierFlags().bits() as u32;
+            raw_modifiers & NX_DEVICELSHIFTKEYMASK != 0
+        }
+
+        pub fn rshift_pressed(&self) -> bool {
+            let raw_modifiers = self.modifierFlags().bits() as u32;
+            raw_modifiers & NX_DEVICERSHIFTKEYMASK != 0
+        }
+
+        pub fn lctrl_pressed(&self) -> bool {
+            let raw_modifiers = self.modifierFlags().bits() as u32;
+            raw_modifiers & NX_DEVICELCTLKEYMASK != 0
+        }
+
+        pub fn rctrl_pressed(&self) -> bool {
+            let raw_modifiers = self.modifierFlags().bits() as u32;
+            raw_modifiers & NX_DEVICERCTLKEYMASK != 0
+        }
+
         pub fn lalt_pressed(&self) -> bool {
             let raw_modifiers = self.modifierFlags().bits() as u32;
             raw_modifiers & NX_DEVICELALTKEYMASK != 0
@@ -178,6 +165,16 @@ extern_methods!(
             let raw_modifiers = self.modifierFlags().bits() as u32;
             raw_modifiers & NX_DEVICERALTKEYMASK != 0
         }
+
+        pub fn lcmd_pressed(&self) -> bool {
+            let raw_modifiers = self.modifierFlags().bits() as u32;
+            raw_modifiers & NX_DEVICELCMDKEYMASK != 0
+        }
+
+        pub fn rcmd_pressed(&self) -> bool {
+            let raw_modifiers = self.modifierFlags().bits() as u32;
+            raw_modifiers & NX_DEVICERCMDKEYMASK != 0
+        }
     }
 );
 
@@ -187,8 +184,14 @@ unsafe impl NSCopying for NSEvent {
 }
 
 // The values are from the https://github.com/apple-oss-distributions/IOHIDFamily/blob/19666c840a6d896468416ff0007040a10b7b46b8/IOHIDSystem/IOKit/hidsystem/IOLLEvent.h#L258-L259
+const NX_DEVICELCTLKEYMASK: u32 = 0x00000001;
+const NX_DEVICELSHIFTKEYMASK: u32 = 0x00000002;
+const NX_DEVICERSHIFTKEYMASK: u32 = 0x00000004;
+const NX_DEVICELCMDKEYMASK: u32 = 0x00000008;
+const NX_DEVICERCMDKEYMASK: u32 = 0x00000010;
 const NX_DEVICELALTKEYMASK: u32 = 0x00000020;
 const NX_DEVICERALTKEYMASK: u32 = 0x00000040;
+const NX_DEVICERCTLKEYMASK: u32 = 0x00002000;
 
 bitflags! {
     pub struct NSEventModifierFlags: NSUInteger {