[1076] ui/plus: Approve dataset classification button

[ssangervasi]

Closes #1076

Code Changes

• "Approve classification" button for datasets that need review
  • This makes two API calls: the normal dataset update call and then a new endpoint for tracking this status.
  • There is a unit-tested function for creating the dataset update body. This uses immer as an explicit dependency,
    but it was already pulled in by RTK.
• Move classify status field to be per-dataset
  • Discussion: https://github.com/ethyca/fidesctl-plus/pull/106#discussion_r980343600
  • This required some selector restructuring. It's kind of nice we usually only need the
    ClassifyDataset instead of the instance itself.

Steps to Confirm

• The classify logic still must be run within cypress.
• The dataset viewing and editing should still work when Plus/Cls is unavailable.

Pre-Merge Checklist

• All CI Pipelines Succeeded
• Documentation Updated:
  • documentation complete, or draft/outline provided (tag docs-team to complete/review on this branch)
  • documentation issue created (tag docs-team to complete issue separately)
• Issue Requirements are Met
• Relevant Follow-Up Issues Created
  • Integrate finalized API endpoints #1120
• Update CHANGELOG.md

Description Of Changes

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[allisonking]

looking good! just some nits. awesome tests!