Rename EE2 variables with `NET` from `VARgfs` to `VARglobal` (or similar)

[DavidHuber-NOAA]

What new functionality do you need?

As the global workflow expands beyond the GFS, it needs to be more flexible for operationalization. EE2 standard variables like HOMEgfs and PARMgfs should be generalized for development. One option is to rename them to VARglobal, but other options may work as well.

In addition, a pre-operational script should be added to dev/ush to perform a sed search and replace of global (or similar) with ${NET} that can run before hand-off. The installation instructions should be updated accordingly for NCO SPAs that need to install the package.

Acceptance Criteria

• All standard variables such as HOMEgfs should be renamed to HOMEglobal (or similar)
• A sed-based script should be written to search and replace all instances of global with the input NET as an argument to the script
  • This script should only look for specific instances (e.g. HOMEglobal, PARMglobal) and not a blanket search/replace of global with NET
• CI tests pass when run before and after running the script
• (Bonus, can be a follow-up issue) a script to convert VAR${NET} back to VARglobal.

Suggest a solution (optional)

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