Add support for the 'ga:segment' dimension with segment IDs

[alastairstuart]

Problem

• GA allows reports to be filtered by a list of standard and user editable segments (e.g only Chrome Users, only sessions with Transactions etc).
• These segments are viewable and editable via GA's web interface.
• Use of ga:segment as a dimension via the Reporting API requires either segment IDs or segment definitions
• https://developers.google.com/analytics/devguides/reporting/core/v3/segments

Proposed changes

• This PR adds support for a new top level report config segments when 'ga:segmenthas been added todimensions`
• segments contains a list of segment IDs
• Segment IDs are stored in the catalog/properties.json in a metadata field for the 'ga_segment' dimension property
• Segment IDs are added to the GA query if they exist
• README has been updated with an example

Types of changes

What types of changes does your code introduce to PipelineWise?
Put an x in the boxes that apply

• 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