Add tests for reset() on sliderInput using dates

[daattali]

Add the following inputs to the reset app:

    sliderInput(
      "date2", "date2",
      min = as.Date("2010-01-01"), max = as.Date("2010-10-01"),
      value = c(as.Date("2010-04-10"), as.Date("2010-07-10"))
    ),
    sliderInput(
      "datetime", "datetime",
      min = to_posix("2010-01-01 10:00:00"), max = to_posix("2010-10-01 16:00:00"),
      value = to_posix("2010-04-09 14:00:00")
    ),
    sliderInput(
      "datetime2", "datetime2",
      min = to_posix("2010-01-01 08:00:00"), max = to_posix("2010-10-01 11:00:00"),
      value = c(to_posix("2010-03-09 19:00:00"), to_posix("2010-07-16 22:00:00"))
    )

Blocked by https://github.com/rstudio/shinytest2/issues/206