Wasted space in <rh-tile> due to arrow

[marionnegp]

When there's no footer content next to the arrow, <rh-tile> shows a lot of empty space at the bottom. Is there a good way to reduce the height of each tile in this instance? @wesleymiles set up a comparison of our tile with some other cards and tiles as examples.

Potential solutions:

• reduce space for arrow when footer content slot isn't used
• reposition arrow when footer content slot isn't used
• maybe we can implement either of the above changes in compact tile only?

[bennypowers]

We are able to detect with js if footer content is present and adjust layout to suit

CC @zhawkins wrt the performance aspects. A future version of lit SSR may enable us to block HTML streaming in order to parse slotted children. In the mean time, we're developing has-slotted hint attributes, which content authors or CMS' could use to assert the presence of slotted content to ssr processes.

[bennypowers]

This came up yesterday on a call with @diwanshi. Collapsing the whitespace when there is no footer content would help sell the use of tile, and it's included usability affordance (the arrow) to design teams.