CE2COAST recipe to compare CMIP6 data over regional oceanic domains

[tomaslovato]

In the framework of CE2COAST project (https://www.ce2coast.com/),
we aim to use ESMValtool to generate regional scale assessment of CMIP6 models,
to support the development of downscaling activities.
CE2COAST project is funded through JPI Oceans and JPI Climate.

Following indications provided by @zklaus, I opened this issue to:

1. include the project within the config-references.yml list
2. contribute to ESMValTool with example recipe(s) for regional assessments developed within CE2COAST

[zklaus]

Nice! I think in principle you can open a new issue for every recipe you want to integrate and just include the addition to the project list in the corresponding PR.

[tomaslovato]

@zklaus thanks for your feedback!
I think I can use the present issue by revising the title to appropriately match the recipe scope.

[tomaslovato]

@zklaus I made few modifications to the ESMValCore code as well to have this recipe (and the related code changes) working... Do you agree if I open an issue on ESMValCore and I create a ce2coast branch in there as well?
In addition there are several update to the cmor fix for CMIP6 ocean variables that I can also include.

I added few features to the ocean timeseries script to enable plotting climatological data... @ledm do you see any overlap/mismatch in these changes with respect to your on-going developments?

[zklaus]

@tomaslovato opening an issue in the core is definitely the way to go. 👍