Use dropdown for session options when many choices

[leafty]

The button group used for session options is replaced with a dropdown
menu when there are more than 5 choices. This is done to avoid choices
spilling over other options.

Fixes #2237.

/deploy #persist #cypress

[leafty]

Current UI, without a lot of styling:

Note: the dropdown is configured to go "down" but I think it goes up because there are too many options.

[RenkuBot]

You can access the deployment of this PR at https://renku-ci-ui-2461.dev.renku.ch

[lorenzo-cavazzi]

Nice solution using CSS modules!

Apart from a couple of linting errors to fix, it would be nice to use the same thicker border already in use for the selected radio button. Otherwise, it feels "unselected".

I noticed the size is also slightly different; perhaps it's related to the borders? Please double-check it again after adjusting borders just to be on the safe side 😁

[leafty]

Added a helper function to estimate the size of the button group and use the dropdown when > 250px.

[lorenzo-cavazzi]

Excellent solution, it works well!

[RenkuBot]

Tearing down the temporary RenkuLab deplyoment for this PR.