Enhancement: Add expand_string logic similar to begin_end_incr

[georgemccabe]

The begin_end_incr syntax can be used to expand a METplus config value into a list by a list of numbers. For example:

LEAD_SEQ = begin_end_incr(0,45,15)M

expands to

LEAD_SEQ = 0M, 15M, 30M, 45M

Describe the Enhancement

Add support for an expand_string function that can be used to expand out a list of string. For example:

POINT_STAT_MASK_POLY = /some/path/for/my/stations/expand_string(DENVER,MINNEAPOLIS,HOUSTON).nc

will expand to

POINT_STAT_MASK_POLY =
  /some/path/for/my/stations/DENVER.nc,
  /some/path/for/my/stations/MINNEAPOLIS.nc,
  /some/path/for/my/stations/HOUSTON.nc

Time Estimate

1-2 days

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