Add-country-specific-costs

[Tomkourou]

Closes #63

Changes proposed in this Pull Request

Checklist

• [ ] Code changes are sufficiently documented; i.e. new functions contain docstrings and further explanations may be given in doc.
• [ ] Data source for new technologies is cleary stated.
• [ ] Newly introduced dependencies are added to environment.yaml (if applicable).
• [ ] A note for the release notes doc/release_notes.rst of the upcoming release is included.
• [ ] I consent to the release of this PR's code under the GPLv3 license.

[Tomkourou]

A fair bit of refactoring is going to be required if I am to use some of the functions available in compile_cost_assumptions.py. For now I have simply copied as little as I could (anything that does require refactoring) into a separate global costs. script and created a global folder inside output.

I need to check whether the numbers make sense, but the basic workflow is now working for DEA Indonesia data.