Templates: add smart rollup node template

Context

I previously introduced smart-rollup-proto template but smart-rollup-node is another project. Creating the merge request so we converge to a nice template.

Manually testing the MR

I haven't tested this mr yet. I need to make sure scoru::node and %Smart Rollup Node and UX works

Works fine, see https://gitlab.com/vch9/tezos/-/merge_requests/12. If you want to manually test:

$ git checkout master
$ git cherry-pick 87c3ae4614d6bbd0501f6e6c03e4ad1f58daa71a
$ git push <your-fork> master -f
$ git checkout -b foo; touch foo; git add foo; git commit -m "foo"
$ git push <your-fork> foo

Then open a merge request targeting <your-fork>/master and try to apply the template.

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR