Add support for transferring postgres range types as json objects

[gwax]

Problem

tap-postgres silently drops postgres range columns

Proposed changes

Add schema and marshalling support for for postgres range types via custom marshalling. We convert the incoming psycopg2.extras.Range object to a json object of the form {"lower": 0, "upper": 5, "bounds": "[)"}. This structure can be parsed and used in a downstream transform to reconstruct the contents of the original source range.

Types of changes

What types of changes does your code introduce to PipelineWise?

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• Description above provides context of the change
• I have added tests that prove my fix is effective or that my feature works
• Unit tests for changes (not needed for documentation changes)
• CI checks pass with my changes
• Bumping version in setup.py is an individual PR and not mixed with feature or bugfix PRs
• Commit message/PR title starts with [AP-NNNN] (if applicable. AP-NNNN = JIRA ID)
• Branch name starts with AP-NNN (if applicable. AP-NNN = JIRA ID)
• Commits follow "How to write a good git commit message"
• Relevant documentation is updated including usage instructions

[gwax]

@Samira-El , @louis-pie : I have rebased and updated this PR against master and have added unit and integration tests to cover the behavior. We have also successfully used it in a production context.

Could you please review so that the functionality can make its way into the mainline codebase?