Follow up to I3484a790ce8ebadf21054ac1d222d5632b2dc5a4
__Template__
The template is not particularly useful - it is only ever
used once in this context and features a static ID which means
it can never be reused. It is also tied to the #vector-toc-collapsed-checkbox
element. In current form it doesn't make sense to have this template.
Maybe in future, I could see an argument for a PinnableTableOfContents component
that wrapped the checkbox and nav element, and generalized the IDs but
currently there's no pressing need or value for that.
__Layouts__
The existing Pinned and Unpinned stylesheets are concerned with how the table
of contents is layed out holistically with regards to other components and
features enabled on the page. I think these should therefore be organized as such.
The way I reason with this, is these styles would be irrelevant in a component
library if the component was rendered in isolation.
Bug: T328719
Change-Id: I9ff0e0eeb35f215a8cae5950d08dc1277b662a71
