Add fixes for administrative codes

[ekatef]

A PR created for demonstrating purposes to support running the model for Canary Islands (IC country code).

The main issue is that Canary islands administratively belong to Spain which means that it's possible to load inputs for them only together with data for mainland country. A better approach should definitely exist, and probably can be developed as a part of pypsa-distribution model.

Checklist

• I consent to the release of this PR's code under the AGPLv3 license and non-code contributions under CC0-1.0 and CC-BY-4.0.
• I tested my contribution locally and it seems to work fine.
• Code and workflow changes are sufficiently documented.
• Newly introduced dependencies are added to envs/environment.yaml and doc/requirements.txt.
• Changes in configuration options are added in all of config.default.yaml and config.tutorial.yaml.
• Add a test config or line additions to test/ (note tests are changing the config.tutorial.yaml)
• Changes in configuration options are also documented in doc/configtables/*.csv and line references are adjusted in doc/configuration.rst and doc/tutorial.rst.
• A note for the release notes doc/release_notes.rst is amended in the format of previous release notes, including reference to the requested PR.

[ekatef]

Closing to avoid distraction. We can continue on modeling remote parts of the larger countries on Discord or opening a thread in discussions if needed