mapml-viewer controls attribute/property does not work as an API

[kevinkim31]

• Fix mapml-viewer & web-map so they can be created via domAPI. closes document.createElement("mapml-viewer") fails #673
• Fix issue where layer control fails to appear when added programmatically (first layer only). closes Appending a layer to layer-less map does not add layer controls  #672
• Add domAPI testing
• Get Testing working for web-map, using:
  • viewer = document.createElement("map", {is:"web-map"})
  • viewer.setAttribute("is","web-map")
• Fix issue where controls fails to hide/disappear when removed programmatically
• Add 'controlslist' as an attribute and make it work through using the API
  • implement 'controlslist' as a DOMTokenList
  • implement DOMTokenList as a class to help support it's methods
• _changeWidth and _changeHeight are causing errors in the console now (on web-map, same thing with mapml-viewer, when map created with width and height attributes it throws an error), as the _container does not get created in the constructor anymore, and is generated afterwards in the connectedcallback

closes #675

[AliyanH]

Added a relatively big commit 9717c44 to reimplement setControls(), which now allows the controls and controlslist API to function properly, Changes made:

• Added support for controlslist attribute, which is now represented by a DomTokenList
• Deconstructed the setControls function to 2 separate functions:
  • setupControls() - creates the controls
  • setControls() - which sets the controls visibility using the hidden attribute based on the map's control and controllist attribute
• Modified old test to change from looking for deleted controls to now looking for the hidden controls
• Added Dom API tests (more tests possibly needed)
  • need to add tests for web-map which currently does not work when the map is created using document.createElement
• Removed duplicate test files (domApi.test.js + domApi.html)
• TODO - create a DomTokenList class for controlslist?

[AliyanH]

f360179 - Added DomTokenList for the map's controlsList, removed getter and setter for the controlslist attribute, though controlslist attribute can still be set using setAttribute to emulate the behavior from the video element.

Few notes/questions:

• jshint is throwing errors for build (when making private properties in the new class), possibly due to Experimental support for class fields jshint/jshint#3139

• currently the controlsListDomTokenList.js is added directly to the dist dir, is this appropriate?

• Need to add DomTokenList Specific tests

[prushforth]

Just a few comments

[prushforth]

LGTM, merge when you're happy with it.