Fixes https://github.com/coder/coder/issues/15972
Adds `keep_locally = true` to other templates that use the
`docker_image` resource to prevent the docker provider from attempting
to remove the image upon workspace deletion.
We had set this in some other places (such as the `dogfood` template)
but had not set this consistently in other templates.
This PR changes template names and docs to follow the
`<provider>-<os/whatever>` format for all templates.
I've decided not to split this into multiple PRs because I'd have to
edit rebase the other PRs once one of them gets merged, this should be
relatively low-impact anyways.
This aligns with our goals to make templates more user-friendly.
Closes#15754
