use mpasout for MPAS data assimilation and forecast initialization (mpasjedi v3.0.1)

[guoqing-noaa]

From MPAS v8.2 and MPASJEDI v3.0, we can use mpasout files to do data assimilation and warm start a new forecast
(note: we can also use mpasout previously, but since the above versions, mpasjedi is fully integrated with the latest mpas model and doesn't need a self-contained mpas model. This enables us to use GSL's version of the MPAS model in data assimilation without any known glitches)

We need a few latest updates in mpas-jedi and all these updates depend on the use of mpasout
So we create a separate ticket for this work.

(There is another related issue #130 but that issue focuses on 2mT/10m wind data assimilation)

[guoqing-noaa]

As a first step test, we can now add pressure fields into init.nc files and this enables us to do data assimilation for the cold start cycle.

[guoqing-noaa]

@Junjun-NOAA is working on update RDASApp to use the latest mpasjedi v3.0.1.

[guoqing-noaa]

Here is Junjun's fork and branch:

https://github.com/Junjun-NOAA/RDASApp/commits/mpasjedi3.0.1/