add tests and fixes to validate builtin processes core script

[fmigneault]

Changes

• Add more tests to validate core code paths of builtin Process jsonarray2netcdf, metalink2netcdf and file_index_selector with validation of happy path and error handling conditions.

Fixes

• Fix invalid parsing of XML Metalink files in metalink2netcdf. Metalink V3 and V4 will now properly consider the namespace and specific content structure to extract the NetCDF URL reference, and the Process will validate that the extracted reference respects the NetCDF extension.

[codecov[bot]]

Codecov Report

Merging #583 (25be10b) into master (7392618) will increase coverage by 0.26%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #583      +/-   ##
==========================================
+ Coverage   84.91%   85.18%   +0.26%     
==========================================
  Files          79       79              
  Lines       17952    17959       +7     
  Branches     2720     2721       +1     
==========================================
+ Hits        15244    15298      +54     
+ Misses       1980     1933      -47     
  Partials      728      728              

Files	Coverage Δ
weaver/processes/builtin/file_index_selector.py	100.00% <100.00%> (+38.70%)	:arrow_up:
weaver/processes/builtin/jsonarray2netcdf.py	100.00% <100.00%> (+43.90%)	:arrow_up:
weaver/processes/builtin/metalink2netcdf.py	100.00% <100.00%> (+44.44%)	:arrow_up:
weaver/xml_util.py	100.00% <100.00%> (ø)

... and 3 files with indirect coverage changes