coreos: use Vue render function instead of templating
Use the render() function rather than Vue templating, and use the
Vue runtime-only build [1]. This is so that the eval() function, which
the CSP blocks, in the Vue full build is not used. Conversion of
previous template logic to using `createElement()` is done accordingly.
Drop generated runtime JS files that are not needed anymore, which were
added in a9fb7591b4a77a9c4baca6f3e8fbb0405a2f71fd.
Also improve the general structure of the code, by adding a `streamDisplay`
data member, which holds display information for the downloadable images
in each section. This structure is populated whenever stream data is
refreshed, by `loadStreamDisplay()`. The `render` function then reads
from `streamDisplay`.
Finally, some minor tweaks to spacing and text are made on the page,
however the page renders largely the same as before.
[1] https://vuejs.org/v2/guide/installation.html#Runtime-Compiler-vs-Runtime-only
Signed-off-by: Robert Fairley <rfairley@redhat.com>