adjust results location resolution to pass references between Workflow steps

[fmigneault]

Changes:

• Add map_wps_output_location utility function to handle recurrent mapping of weaver.wps_output_dir back and
  forth with resolved weaver.wps_output_url.
• Add more detection of map-able WPS output location to avoid fetching files unnecessarily. Common cases
  are Workflow running multiple steps on the same server or Application Package Process that reuses an output
  produced by a previous execution. Relates to [Feature] Explicit 'fetch' parameter for some given input #183.

Fixes:

• Fix incorrect resolution of Process results endpoint to pass contents from one step to another
  during Workflow execution (resolves Missing parameter value in workflow #358).

ToDo

• add proper test for workflow, relates to:
  • Increase test coverage #141
  • Resolve broken tests for Workflows #281
• integrate pending PRs for 4.3 prior to this one in 4.4
• adjust changes/fixes location in changelog

[dbyrns]

Nice job!

[codecov]

Codecov Report

Merging #360 (0d9d2e8) into master (eccd2ed) will increase coverage by 0.50%.
The diff coverage is 76.82%.

@@            Coverage Diff             @@
##           master     #360      +/-   ##
==========================================
+ Coverage   78.24%   78.74%   +0.50%     
==========================================
  Files          63       63              
  Lines       10406    10469      +63     
  Branches     1564     1582      +18     
==========================================
+ Hits         8142     8244     +102     
+ Misses       1773     1726      -47     
- Partials      491      499       +8     

Impacted Files	Coverage Δ
weaver/typedefs.py	0.00% <ø> (ø)
weaver/processes/sources.py	46.29% <25.00%> (+1.85%)	⬆️
weaver/processes/builtin/__init__.py	72.27% <33.33%> (-1.00%)	⬇️
weaver/wps/utils.py	74.12% <58.82%> (-6.45%)	⬇️
weaver/processes/wps_workflow.py	50.79% <66.66%> (+1.27%)	⬆️
weaver/utils.py	81.56% <76.92%> (+0.20%)	⬆️
weaver/processes/wps3_process.py	57.39% <79.22%> (+7.13%)	⬆️
weaver/processes/wps_package.py	77.82% <82.35%> (+5.92%)	⬆️
weaver/config.py	77.55% <100.00%> (ø)
weaver/processes/execution.py	82.05% <100.00%> (+0.05%)	⬆️
... and 12 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update eccd2ed...0d9d2e8. Read the comment docs.