feat(screener): add screener tests with steps

[silviuaavram]

Edited screener.config.js to check for test files that have tests with steps. Also edited the states property gets created.

Added shorthand for triggerButton in Dropdown so I can add a test id attribute to it, for better and safer selection in screener (and future e2e) tests. Edit: if we decide to use className, will leave the shorthand for now, it is still useful.

[layershifter]

As we already have glob in dependencies I have a proposal to place steps files near with examples, i.e:

DropdownExampleSingleSelection.shorthand.tsx
DropdownExampleSingleSelection.steps.js

Then resolve these files via glob and use them, this will also allow to simplify structure of file:

module.exports = (Steps) => ([
  {
     name: 'Shows List',
     steps: new Steps()
       .click(selector('CLASSNAME'))
       .snapshot('Snapshot')
       .end(),
  },
])

[layershifter]

LGTM except two comments, fix them please before merge 🐱

Also it will be nice to hear feedback from @kuzhelov before merge

[bmdalex]

looks good, one small comment

[mnajdova]

🥇 Let's just create issue for the problems with using JS files here, as we are aware at this moment that we have problems when we want to import something from TS files.