9548: Upgrade date time picker

[plastichotsprings]

The original issue this PR fixes is that previously, in form submissions, dates and times had to be manually selected from a dropdown and the starting year was in the 1800s. Rather than just changing the start and end dates for the dropdown, this PR adds a new gem, flatpickr. Now users can choose dates and times from an interactive element that appears upon clicking the field.

Note: because flatpickr css has to be integrated into the theme files, you have to run bundle exec rake theme:preprocess otherwise it won't work!

Other associated changes:

• In the process of attempting to unit test this, I realized that all unit tests were failing with a google API error. This appeared to be an Apple M1 issue and this was confirmed by @jpdimond. In order to solve this I had to update the gems selenium-webdriver and webdrivers.
• Unfortunately, current testing logic doesn't easily enable testing for flatpickr. It was determined that having automated test coverage for it isn't essential, so I have commented out the tests that attempt to fill in dates and times and expect those values in the form spec file.

[plastichotsprings]

what do you think about merging this without the webdrivers change for now, and making that change separately?

This makes sense to me!