Transfer selected blocks from global_variables to case metadata

[perolavsvendsen]

First stab at partial solving of #337

This PR will transfer selected blocks from global_variables.yml into case metadata, when they exist.

[perolavsvendsen]

Note that:

• The list of blocks to fetch from global_variables is predefined in fmu-dataio. E.g. a random user can not specify a "random" block. In other words; a standard is inferred here. Not sure if this actually exists.
• If a requested block does not exist, or has a different type than expected, warn and move on. We do not want the generation of case metadata to fail at this point, because debugging that from an end user perspective is close to impossible as long as this runs in a HOOK workflow. (The main FMU run will move on regardless of success of the HOOK or not, so if this fails, user will experience failure on all later uploads but it will not be intuitive what caused it.)

[daniel-sol]

I see that the definition of blocks to be in the case metadata seems logical, but isn't it a bit challenging with the contacts and other relevant things, could be volume factors etc.

[perolavsvendsen]

In this proposal, only one new block in the (case) metadata, which is fmu.case.config. And then "whatever" into that. I.e. we don't validate in detail, so fmu-dataio can technically include anything into that block.

But given the ongoing discussion around parameters.txt where we are leaning towards having that as a separate data object, we might discuss this PR in that perspective as well. Should case config be a separate data object? 🤷‍♂️

[perolavsvendsen]

And, another point - which is possibly what you meant - is access control and information classification. We cannot have a situation where someone is to be granted access to only parts of the case metadata, that would not work.