feat: Allow skipping validation when constructing workspaces

[alexander-held]

Description

This adds a validate kwarg to the Workspace constructor and to Workspace.build, replicating the existing functionality in Model to skip validation against the JSON schema. For complex workspaces / models, where validation can take an appreciable amount of time (see #1699), this can be a useful option if users are sure that their inputs follow the required format.

There are two things in here that are optional, I tried to split them across commits to easily take out anything you may not want:

• added typing for the validate kwargs,
• moved the log info about reference schema to only trigger if validation is actually performed.

There was previously no documentation for validate in the Model constructor, so this has also been added.

A test for workspace construction without validation is also included, for both construction from a specification and from model + data. This uses the same simplemodels setup also used elsewhere in the workspace tests, so this could be refactored if #1709 is merged first (or otherwise could be refactored in #1709). Since #1709 also adds a test at the end, merging one probably results in a conflict with the other PR as well. -> #1709 was merged before, and the implementation here was changed to re-use the fixture added in that PR.

resolves #1699

Checklist Before Requesting Reviewer

• Tests are passing
• "WIP" removed from the title of the pull request
• Selected an Assignee for the PR to be responsible for the log summary

Before Merging

For the PR Assignees:

• Summarize commit messages into a comprehensive review of the PR

* Add validate kwarg to pyhf.workspace.Workspace to allow skipping validation
if the user desires.
   - The motivation for this comes from some workspace validations taking
     multiple seconds. Power users might want the ability to turn off
     validation in these cases to save time. This behavior is discouraged
     in general, but should be allowed.
* Add docstring for pyhf.workspace.Workspace and add validate kwarg to
pyhf.pdf.Model docstring.
* Add tests for workspace validate kwarg.

[codecov]

Codecov Report

Merging #1710 (e506094) into master (43c1567) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1710   +/-   ##
=======================================
  Coverage   98.12%   98.12%           
=======================================
  Files          64       64           
  Lines        4269     4270    +1     
  Branches      682      683    +1     
=======================================
+ Hits         4189     4190    +1     
  Misses         46       46           
  Partials       34       34           

Flag	Coverage Δ
contrib	26.25% <28.57%> (-0.01%)	⬇️
doctest	60.58% <71.42%> (-0.02%)	⬇️
unittests	96.18% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/pyhf/pdf.py	97.80% <100.00%> (ø)
src/pyhf/workspace.py	100.00% <100.00%> (ø)

---

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 43c1567...e506094. Read the comment docs.

[matthewfeickert]

Relevant RTD builds:

• pyhf.pdf.Model
• pyhf.workspace.Workspace

[matthewfeickert]

Thanks for the PR @alexander-held. This all is looking good to me and your plan for docstrings sounds great. 👍

[matthewfeickert]

Okay this one can get rebased and refactored now. 👍

[kratsg]

Congrats on the 1k'th commit @alexander-held :)