feat(layout_column_wrap): Allow items to be smaller than min width

[gadenbuie]

Non-breaking change from #799

When width is a CSS unit (i.e. not a fractional unit between 0 and 1) and fixed_width = FALSE, this PR changes the value for grid-template-columns from

repeat(auto-fit, minmax({width}, 1fr))

to

repeat(auto-fit, minmax(min({width}, 100%), 1fr))

The result is that the items in a column-wrapped layout no longer overflow their container if the container width is less than the specified width (unless fixed_width = TRUE, of course).

Example

# Open me on a medium sized screen (i.e., between about 800-500px) 
# and notice how the cards "bleed outside" of their containing column

my_card <- card(lorem::ipsum(2), max_height = 100)

page_fixed(
  layout_column_wrap(
    width = "800px", 
    class = "border border-danger",
    !!!replicate(3, my_card, simplify = F)
  )
)

Before	After