Enhance the config file parser logic to allow for empty dictionaries

[JohnHalleyGotway]

Describe the Enhancement

dtcenter/METplus#1853 issue is to enhance enable the METplus PointStat wrapper to run without error when no mask is provided. The default Point-Stat configuration file includes:

mask = {
   grid  = [ "FULL" ];
   poly  = [];
   sid   = [];
   llpnt = [];
}

However, when no masks are actually defined via METplus, the mask dictionary defined by METplus is empty:

mask = { }

However this results in a parsing error from MET. This behavior can be replicated by running:

> echo "a = {}" > test
> test_config test
ERROR  : yyerror() -> syntax error in file "/tmp/met_config_70366_0"
ERROR  : a = {}
ERROR  : __^___

This issue is to update the logic of the config file parser to allow for the use of empty dictionaries.

Time Estimate

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Issues should represent approximately 1 to 3 days of work.

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