Added several Mission atlantic developments and a shelve fixer tool

[ledm]

Lots of Mission Atlantic fixes and an entirely new tool.

So this affects a lot of files (51!), but most of them are Mission Atlantic yml files, so nothing too major.

A new tool, revert_shelve (possibly not the best name - happy to change it), now takes a few command line arguments and allows the deletion of specific years and months of processed data in the bgcval2 shelve datasets. This was needed because we found a fault in the MA runs and needed to go back and re-simulate a few years.

In terms of actual changes:

• analysis_compare output plots path includes the metric so that max no longer overwrites mean plots.
• Mission Atlantic files are no longer requires to be prefaced with SENEMO and can keep the standard /YEAR/MN/ directory structure. (This is why all MA files have been changed.)
• Several compatibility fixes for MA data format in the time series analysis and analysis_compare tool.

[valeriupredoi]

can you also add to the executables list and add a basic run test for it in the github action, pls?