improve checkProjectSummations for NGFS + ELEVATE + ScenarioMIP

[orichters]

Purpose of this PR

• allow to pass more than one mapping
• specify whether bunkers units should be ignored dependent on mapping (TRUE for AR6 only)
• check all mappings for missing variables

Type of change

• Minor feature improvement

Checklist:

• No code affects 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
• not needed: I checked that the in-code documentation is up-to-date
• not needed: I adjusted the reporting in remind2
• not needed: I adjusted forbiddenColumnNames in readCheckScenarioConfig.R in case the PR leads to deprecated switches
• All automated model tests pass (FAIL 0 in the output of make test)
• not needed: The changelog CHANGELOG.md has been updated correctly