Integrate ARO observations into the workflow and rename RDA to GDEX (#428)

[jim-p-w]

Description

Adds end-to-end support for ARO (airborne GNSS-RO) observations processing and assimilation with MPAS-JEDI. This includes integrating the gnssaro download and conversion pipeline into GetObs.csh and ObsToIODA.csh, with observation format (netcdf or bufr) and source (nrt or postProc) configurable through new observations.yaml options (AROFormat, AROSource, AROPostProcRelease, and AROVersion).

The PR also adds support for the `gnssaro_bufr2ioda.py` converter, introduces a `gnssarobndropp2d` YAML stubs for da and hofx configuration, adds new workflow scenarios for ARO processing and assimilation, and renames GladeRDAOnline to GDEXOnline throughout the workflow.

**Note:** AROFormat: bufr is currently incompatible with AROSource: postProc because AGS post-processed bfrPrf files use a BUFR encoding that eccodes cannot decode. This unsupported configuration is detected during configuration with a clear error message, preventing failures later during batch execution.

Issue closed

Closes #(if applicable)

Tests completed

Tier 1:

• 3dvar_OIE120km_WarmStart
• 3denvar_OIE120km_IAU_WarmStart
• 3dvar_OIE120km_ColdStart
• 3dvar_O30kmIE60km_ColdStart
• 3denvar_O30kmIE60km_WarmStart
• eda_OIE120km_WarmStart
• getkf_OIE120km_WarmStart
• ForecastFromGFSAnalysesMPT
• 4denvar_OIE120km_WarmStart
• 4dhybrid_OIE120km_WarmStart

Tier 2 (optional):

• GenerateGFSAnalyses
• GenerateObs

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