FMA for Fusaka Compatibility

[geoknee]

Can be a reworking of this doc https://www.notion.so/oplabs/Impact-of-Fusaka-on-OPStack-233f153ee1628041a9aaf8f172076048

Should go into detail about the proposed solution here https://www.notion.so/oplabs/P-PS-Fusaka-Defence-Upgrade-Release-Strategy-27ef153ee1628002811fda9b4baf25b2?d=27ef153ee162805b9e24001cdbe7add0#27ef153ee162804cb7acf53cdb2eea9a and any particular risks that arise there.

[geoknee]

If we do the "cherry pick" approach, we should also perform a careful analysis of the git diff to the full upstream release to see what we are missing out on.

[geoknee]

PR here #341