Enable E3SM shared pi in MPAS-Ocean

[cbegeman]

This PR enables the use of E3SM shared constant pi in MPAS-Ocean when run in coupled configurations.

[cbegeman]

@xylar In addition to your #6481, do we want to include the changes I have here as a separate PR?

[rljacob]

Does this change answers for coupled cases?

[xylar]

@rljacob, I think these will be answer changing for all runs involving MPAS-Ocean, including coupled runs.

@cbegeman, that is why I had not opted to make these changes yet, though I think they are very desirable.

[cbegeman]

Would you like me to close this PR and reopen at a later date?

[xylar]

@cbegeman. let's see what @rljacob says.

[rljacob]

Leave it open. We'll be making the maint-3.0 branch soon and this can go in after that.

[xylar]

Great, thanks, @rljacob!

[cbegeman]

Thanks, @rljacob and @xylar for your feedback

[xylar]

There are still many places in both shared and analysis_members that use pii from the MPAS framework. These should also be updated to use MPAS-Ocean's pi instead. See include:
https://github.com/search?q=repo%3AE3SM-Project%2FE3SM+pii+path%3A%2F%5Ecomponents%5C%2Fmpas-ocean%5C%2F%2F&type=code

This was taken care of for global ocean init mode in #6481

[cbegeman]

There are still many places in both shared and analysis_members that use pii from the MPAS framework.

Thanks for pointing this out! I didn't think to grep for that spelling. I'll make those changes as well.

[proteanplanet]

We are planning a separate PR for sea ice.

[cbegeman]

We are planning a separate PR for sea ice.

Great. I'll confine this PR to only the ocean component then.