add dependancies to enable tests to run
there is a slight missmatch in html classes in `js.snap` test vectors
when tests are run with storybook is built using `storybook dev` vs
`storybook build`
using svelte format for stories requires storybook to run with the
--index-json flag but this breaks the storage location of DOM
snapshots
the configuration files in this commit fixes this and also moves them
to the same location as the image snapshots
add image and dom snapshot comparison for storybook components
image snapshot comparison can been flaky and produce many
false-positives. a higher threshold has been used to mitigate this
although it may not identify all regressions. DOM snapshots
supplement images to increase the likelihood of capturing
regressions.
DanConwayDev