Update _HasDropDown to leverage dojo/touch::press and dojo/touch::release rather than listening for mousedown/mouseup events that may or may not occur.  Refs #13048 !strict.
Leverage ondijitclick in Calendar, to get the normalized touch handling in dojo/touch plus the keyboard click handling in dijit/a11yclick.  Refs #15878 !strict.
Leverage dojo/touch in !CheckBox and !MultiSelect, to get the normalized touch click handling.  These two widgets are special because they are based on native form controls (<input type=checkbox> and <select multiple>), so they need to get a real click event rather than using a synthetic dojoclick type event.   Luckily (for this case) this is how dojo/touch is currently working, by emitting a click event.  Refs #15878 !strict.