feat: add connectedTerms connection to Taxonomy object

[justlevine]

What does this implement/fix? Explain your changes.

This PR adds a connection from Taxonomy to TermNode, using the connectedTerms field.

{
  taxonomy(id: "category", idType: NAME) {
    connectedTerms {
      nodes {
        name
      }
    }
  }
}

This allows for more generic queries to be made, and is particular useful for post archives:

query getPostTypeArchive( $uri: String ){
  nodeByUri(uri: $uri) {
    ... on ContentType {
      connectedTaxonomies {
        nodes {
          label
          connectedTerms {
            nodes {
              name
              slug
              count
            }
          }
        }
      }
      contentNodes{
        nodes{
          uri
          ... on NodeWithTitle{
            title
          }
          ... on NodeWithContentEditor{
            content
          }
        }
      }
    }
  }
}

Any other comments?

Somewhat related to #2026 , as it creates a relationship between ContentNode and TermNode, albeit by using the ContentType as the intermediary.

Where has this been tested?

Operating System: Ubuntu 20.04

WordPress Version: 5.9.1

[justlevine]

codecept run wpunit is failing because there are leftover categories in the database - assuming because some tests arent cleaning up but I cant pinpoint where.
codecept run tests\wpunit\TaxonomyObjectQueriesTest.php::testTaxonomyQueryForCategories passes.

[jasonbahl]

@justlevine thanks for this PR! 🙏🏻

Yes, this is related to #2026. I hope to get that wrapped up here soon, and I'll include this with that, for sure.

I'm going to get v1.7.0 released first, then circle back to these.

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[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically closed because it has not had recent activity. If you believe this issue is still valid, please open a new issue and mark this as a related issue.

[codeclimate]

Code Climate has analyzed commit 05b3973 and detected 0 issues on this pull request.

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[coveralls]

coverage: 84.558% (+0.03%) from 84.533% when pulling 05b3973 on justlevine:feat/add-connectedTerms-to-taxonomy into a2d5f4e on wp-graphql:develop.