Bug fix of accountig of fossil CCS in CDR sector

[amerfort]

Purpose of this PR

This PR solves this issue in the REMIND code.
Currently, fossil CCS in the CDR sector is not deduced from total fuel combustion (that is calculated in vm_emiTeDetailMkt assuming all fuel is burned and emissions occur for that) in the CDR sector.
This only applies to DAC and OAE and in any case the fossil fuel combustion in the CDR sector is very low. The change does not affect scenario results but is necessary for correct accounting and successful summation checks. CDR emission flows follow the exact same logic as Industry CCS.
This PR should be accompanied by a respective change in the reporting.

I also updated in-code descriptions and improved the name of a variable and a scalar.

Note: As this has to be merged simultaneously with the respective changes in the reporting, this PR is but a draft and I will only merge it, once we decided on the correct accounting of CDR sector emissions in the reporting and I properly tested the changes such that the summation checks succeed.

Type of change

(Make sure to delete from the Type-of-change list the items not relevant to your PR)

• Bug fix
• Minor change (default scenarios show only small differences)

Checklist:

• My code follows the coding etiquette
• I performed a self-review of my own code
• I explained my changes within the PR, particularly in hard-to-understand areas
• I checked that the in-code documentation is up-to-date
• I adjusted the reporting in remind2 where it was needed
• I checked the log.txt file of my runs for newly introduced summation, fixing or variable name errors
• All automated model tests pass (FAIL 0 in the output of make test)
• The changelog CHANGELOG.md has been updated correctly

Further information (optional):

• Runs with these changes are here: /p/tmp/amerfort/fossilCCSaccountingCDRmodule/output
  But be aware, the reporting was not updated in the compare scenarios and due to the variable renaming positive emissions of the CDR sector are not properly calculated.
• Comparison of results (what changes by this PR?):
  No changes for scenarios with no dac and oae. ECBudg scenarios did not converge, so a comparison is difficult. In general, residual emissions are slightly lower and carbon prices are also slightly lower after this fix.