docs: fix type information for contents.sendInputEvent (#19479)

The `event` type and keyword is reserved by the typescript generator, in the future we should throw an error from the generator if someone uses a reserved interface like that.

This also splits and documents the InputEvent type way better so that TS
users get strong type safety.

Fixes electron/typescript-definitions#36

docs/api/structures/input-event.md

@@ -0,0 +1,6 @@
+# InputEvent Object
+
+* `modifiers` String[] - An array of modifiers of the event, can
+  be `shift`, `control`, `alt`, `meta`, `isKeypad`, `isAutoRepeat`,
+  `leftButtonDown`, `middleButtonDown`, `rightButtonDown`, `capsLock`,
+  `numLock`, `left`, `right`.

docs/api/structures/keyboard-input-event.md

@@ -0,0 +1,6 @@
+# KeyboardInputEvent Object extends `InputEvent`
+
+* `type` String - The type of the event, can be `keyDown`, `keyUp` or `char`.
+* `keyCode` String - The character that will be sent
+  as the keyboard event. Should only use the valid key codes in
+  [Accelerator](../accelerator.md).

docs/api/structures/mouse-input-event.md

@@ -0,0 +1,12 @@
+# MouseInputEvent Object extends `InputEvent`
+
+* `type` String - The type of the event, can be `mouseDown`,
+    `mouseUp`, `mouseEnter`, `mouseLeave`, `contextMenu`, `mouseWheel` or `mouseMove`.
+* `x` Integer
+* `y` Integer
+* `button` String (optional) - The button pressed, can be `left`, `middle`, `right`.
+* `globalX` Integer (optional)
+* `globalY` Integer (optional)
+* `movementX` Integer (optional)
+* `movementY` Integer (optional)
+* `clickCount` Integer (optional)

docs/api/structures/mouse-wheel-input-event.md

@@ -0,0 +1,11 @@
+# MouseWheelInputEvent Object extends `MouseInputEvent`
+
+* `type` String - The type of the event, can be `mouseWheel`.
+* `deltaX` Integer (optional)
+* `deltaY` Integer (optional)
+* `wheelTicksX` Integer (optional)
+* `wheelTicksY` Integer (optional)
+* `accelerationRatioX` Integer (optional)
+* `accelerationRatioY` Integer (optional)
+* `hasPreciseScrollingDeltas` Boolean (optional)
+* `canScroll` Boolean (optional)