Focus focus focus

• More closely aligned with WAI ARIA guidelines on focus: now it gives priority to autofocus elements instead of just focusing on the first focusable element (fallback)
• Adds focusRef to delegate consumer what's the appropriate element to focus for each dialog scenario
• Improves and fixes focusTrap error.
• Adds specs for the features and band-aids failing ones
• Tapping esc while on focused on an <input type="search"> will not close the dialog unless the input is empty (default behaviour of this input is to reset the input value and we don't want to interfere with that)
• Fixes a bug where selecting text content within the dialog would remove the possibility of closing the dialog using keyboard

References

• https://www.w3.org/TR/html52/interactive-elements.html#elementdef-dialog
• https://www.w3.org/TR/wai-aria-practices/#dialog_modal