Ensemble instance number label in MOM6 output file names

[kdraeder]

I've run a multi-instance forecast (cesm3_0_beta05) to see the output files,
and I see that MOM6 puts the instance number in a different place than the other components.
${CASE}.mom6.r.1850-01-01-10800 ._0001. nc
${CASE}.cam _0001 .r.1850-01-02-00000.nc
and not even in a consistent place (here it's before the date):
${CASE}.mom6.h.Drake_Passage ._0001 .1850-01.nc.0033

I think that it makes sense to attach the instance number to the component name,
because an instance is an independent copy of that component,
but I don't know how difficult it would be to do that.
That also avoids the slightly awkward '._' notation.

It's very helpful when dealing with large numbers of files and file types
from multiple components if all components use the same naming convention.

[kdraeder]

@alperaltuntas
Thanks for taking this on!
Following up on your email about it; DART works directly with the restart files in all cases,
but only handles history files as diagnostic as desired by a user.
So making the restart file names consistent with the other components would be the most helpful.
Then, if it's not too difficult, making the history file names consistent would be nice.

Of course, other users might have different priorities.