Move ci directory to .cscs-ci

[msimberg]

This is 0% functional change and 100% housekeeping. The ci directory is extremely generically named, and not a hidden directory. I propose to move the CSCS CI files to a .cscs-ci directory to live alongside the already existing .github directory for github workflows.

Note that the CSCS CI config has to be updated in sync with this (since it declares where to find the entrypoint .cscs-ci/default.yml etc.), so the merge of this will need a bit of coordination.

If you consider this unnecessary churn we can close this without any harm.

[github-actions]

Mandatory Tests

Please make sure you run these tests via comment before you merge!

• cscs-ci run default
• cscs-ci run distributed

Optional Tests

To run benchmarks you can use:

• cscs-ci run benchmark-bencher

To run tests and benchmarks with the DaCe backend you can use:

• cscs-ci run dace

To run test levels ignored by the default test suite (mostly simple datatest for static fields computations) you can use:

• cscs-ci run extra

For more detailed information please look at CI in the EXCLAIM universe.