Test selecting time-zone during signup

[pascallaliberte]

The process of selecting a time-zone during sign up is cumbersome because too many clicks are needed to use type-ahead search for super_select field that allow a single selection.

Also, the existing select2_select helper only works with super_select fields that allow multiple selections.

This PR:

• Makes the select2_select helper work with super_select fields that allow only a single selection. It simulates typing into the un-opened field and continues to type with the super_select dropdown opened and the input field in focus.
• Adds a step to authentication_test to select the Time Zone during sign up.

Co-dependent PRs (required for the test to pass):

• super-select: catch keydown and open if not multiple bullet_train-themes#21
• super_select: allow catching keydown and opening on click bullet_train-fields#36

[pascallaliberte]

With the associated PRs, we get this smooth, smooth time-zone-picking flow:

[jagthedrummer]

@pascallaliberte This looks good to me, and it looks like the dependent PRs were replaced by one in core that has already been merged (bullet-train-co/bullet_train-core#63). So is it accurate that this one should be ready to merge now? If so we should re-trigger CircleCI, which I don't have permission to do, so we can make sure that tests are passing. (It looks like they failed previously, but it's been so long that Circle doesn't seem to have those test runs available to inspect anymore.)

[jagthedrummer]

@pascallaliberte I saw that there was a linter error in Circle, so I fixed that, which got a new Circle run to kick off. But now there seems to be a legitimate failure related to these new tests. Can you take a look?

[jagthedrummer]

@pascallaliberte Is this still something you'd like to get merged?

[pascallaliberte]

@jagthedrummer yes, I'll scrub and polish it next week