Initial support for reports

[jtcohen6]

See: dbt-labs/dbt-core#2730, dbt-labs/dbt-core#2752

Describe the feature

We need to extend docs to support a new node/resource type, reports:

• We can use the standard resource page template for now
  • Eventually, we'll want to display cool things and provide interactions based on type, maturity, url, owner
  • Long-term vision: each report acts as a "landing page" for read-only users who may not otherwise have a good grasp of dbt
• Fix the DAG viz in projects that have reports

Describe alternatives you've considered

We gotta do it!

Who will this benefit?

Any & all users of the new report node type