Route of job inputs, outputs and result

[fmigneault]

When a job is completed, it is currently difficult to know where the result came from as we do not have any input indication or any methodology to retrieve this information from the REST API.

We should add jobs/{id}/inputs (and all other job's route variants) that would return the list of input values received during the job submission.

Corresponding outputs route should also be added to match the inputs/outputs fields specified in the process description. This would make it more natural to search for the result as field name mapping would be literally the same keyword.

These routes should be provided in links as per #58.

Route jobs/{id}/result[s] (with and without s) should be kept as aliases to remain back-compatible with existing specifications. They themselves use both variants interchangeably:

• https://raw.githubusercontent.com/opengeospatial/wps-rest-binding/develop/docs/18-062.pdf
• https://app.swaggerhub.com/apis/geoprocessing/WPS/1.0-draft.2#/Result/getResult

Also add a 'request' link for saving the literal body received for the job execution.
Highlighted by @matprov