rename ar6Climate -> MAGICC7_AR6, add cs2 section with all output

[orichters]

Purpose of this PR

• rename ar6Climate -> MAGICC7_AR6. It needs mif files, so add it in output.R to that category
• shorten variable names

    AR6 climate diagnostics|Surface Temperature (GSAT)|MAGICCv7.5.3|67.0th Percentile
 -> MAGICC7 AR6|Surface Temperature (GSAT)|67.0th Percentile

• add own section that allows to see full MAGICC7 output in compareScenarios2 style, using the new plotPercentiles function introduced by @tonnrueter. See /p/tmp/oliverr/remind/compScen-fulltest_MAGICC7_AR6-2024-03-14_15.07.59-MAGICC7_AR6.pdf
• Gross Emissions|CO2 is also a variable that contains bunkers only at the global level, so it must be skipped in aggregation checks
• rename project_interfaces -> piamInterfaces

Type of change

• New feature
• Bug fixes

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
• All automated model tests pass (FAIL 0 in the output of make test): [ FAIL 0 | WARN 0 | SKIP 6 | PASS 80 ]
• The changelog CHANGELOG.md has been updated correctly