Refactor paths and runtime names

[chevdor]

This PR renames the rococo runtime to follow the pattern used by all other chains (in this repo and the pollkadot repo).

The PR also uses the same folder tree (= runtimes under a runtime/<name>) folder. That simplifies tooling and allows building all the runtimes the same way.

Once this PR is merged, I will be able to extend the CI to build statemint, shell and rococo using srtool (see #509)

[bkchr]

I would be fine to move this to polkadot-parachains/runtime/*, but not moving it to the top

[chevdor]

That works for me. The most important is that:

• the rococo runtime is named rococo-runtime
• the runtime <foobar> in the runtime_dir (in our case polkadot-parachains or polkadot-parachains/runtimes) as a foobar folder (vs foobar-runtime currently).

It is easier if the runtime_dir is a folder called runtime as in Polkadot but having it a level down as you suggest is not a big issue.

Let me adjust to your suggestion.

[chevdor]

I don't see a benefit going from polkadot-parachains/* to polkadot-parachains/runtime/* so I will bring the runtimes back to polkadot-parachains/*

[chevdor]

@bkchr would that work for you now ?

[bkchr]

bot merge

[ghost]

Trying merge.

[ghost]

Merge failed with response status: 403 Forbidden and body: {"documentation_url":"https://docs.github.com/rest/reference/pulls#merge-a-pull-request","message":"Resource not accessible by integration"}