Suggest adding a `isCoarse` property?

[mattrq]

Similar to issue Suggest adding a firesHoverEvents property

Suggests that a property isCoarse boolean is added to allow accurate handling of different pointer-based input devices. There are a number of benefits that this allows for by allowing to changing the behaviour based on the support for hover for user interaction and better accessibility handling.

The current methods to detect hover support are not always accurate:

1. Using CSS media queries: The cross-browser support and reliability of those are mixed. A negative query may indicate no support for the query or the current device doesn't support hover.
2. The PointerEvent.pointerType can help by making assumptions for "mouse" (precise input) and "touch" (coarse input), however "pen" may or may not support hover depending on the type of pen in-use.
3. Assuming that fireTouchEvents!==true means that the input is precise.

Example scenarios:

• Different forms of pen inputs have very different capabilities.
• Laptop with mouse and trackpad but coarse input due to accessibility.