Adds 3.1.0 unit test spec

[spacether]

Adds 310 unit test spec

• only v3.0.3 json schema keywords have been turned on at this time. A future PR will turn on the new v3.1.0 json schema keywords + tests
• type array cases included
• Note: draft2020-12 requires that format validation is opt out by default. My expectation is that in code generation contexts, format validation is opt-in by default. So I keep the code opting in to validation on format by default, in in tests, I opt the tests out of format validation. End users may turn off format validation like the tests do if they prefer.

swagger-parser bugs found:

• v3.1.0 min/max/Items/Length/Properties information omitted from schema swagger-api/swagger-parser#1974

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  mvn clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/python*.
  For Windows users, please run the script in Git BASH.