Improve CO2 accounting in exporter

[lindnemi]

The CO2 balance in the Ariadne DB does not cancel out exactly. While there are many minor discrepancies between IAM accounting and our accounting, this PR fixes a major one: CCS from e-fuels had not been correctly accounted so far.

This PR:

• subtracts: efuel -> naptha -> process emissions from CO2|Industrial Processes

• adds: efuel -> naptha -> process emissions -> CC to Sequestration|Other

• adds: efuel -> CC to Sequestration|Other

Open points:

• efuel -> CC should be corrected with oil_fossil_fraction
• small refactor to use co2_stored more consistently for above causes
• add back in the asserts that were disabled to get to exports faster
• Are fossil CC really treated as neutral, or is there more that should be subtracted?
• Figure out remaining difference of 5-10 Mt compared to Ariade accounting, to get to an equal CO2 balance
• Consider Carbon Sequestration in Emissions|CO2 (as well as FOLU?)

Before asking for a review for this PR make sure to complete the following checklist:

• Workflow with target rule ariadne_all completes without errors
• The logic of export_ariadne_variables has been adapted to the changes
• One or several figures that validate the changes in the PR have been posted as a comment
• A brief description of the changes has been added to Changelog.md
• The latest main has been merged into the PR
• The config has a new prefix of the format YYYYMMDDdescriptive_title