add a new stream property 'gattr_update' to control whether to update global attributes

[guoqing-noaa]

When we do coldstart data assimilation on init.nc using JEDI, we will get a crash in MPAS IO with the following error:

ERROR: MPAS IO Error: PIO error -38: NetCDF: Operation not allowed in data mode

Per discussions with NOAA @SamuelTrahanNOAA and NCAR Tao Sun, we identified that the problem came from src/framework/mpas_stream_manager.F where mpas_writeStreamAtt tries to write not-defined global attributes to init.nc. Since we don't expect JEDI to update any global attributes (at least for init.nc), we can skip the relevant mpas_writeStreamAtt part when doing JEDI data assimilation.

This PR is to address this issue by adding a new stream property gattr_update. It takes values of yes or no and defaults to yes. So it does not affect any existing MPAS-Model capabilities but allow coldstart JEDI DA to skip the relevant mpas_writeStreamAtt part to avoid crash, by setting gattr_update=no in the analysis stream.