Linting EVEREST configuration files on changes or overnight

The EVEREST configuration cases can be linted whenever there is a commit, a pull request or overnight using GHA. This is a faster and less computationally intensive way to flag for errors in the config.

Initial proposal with GHA:

```yaml
- name: lint everest configs
run: |
git clone https://github.com/equinor/everest-tutorials.git
TUTORIAL_PATH=$(pwd)/everest-tutorials/data/drogon

echo "Linting $TUTORIAL_PATH/well_rate/everest/model/drogon_wellrate.yml"
config=$TUTORIAL_PATH/well_rate/everest/model/drogon_wellrate.yml
sed -i '/^ simulation_folder:/d' $config
everest lint $config
```