Clean up a few things in tests

[grahamalama]

• remove unused mocks
• use typescript with our test utils module, and make camelCase while we're at it
• Delete duplicate createComponent util
• Tweak renderWithProvider to look like what's suggested in testing-library / redux docs
• instead of doing

  const node = render(<Component />)
  expect(node.query(...))

  do

  render(<Component />)
  expect(screen.query(...))

  as is demonstrated throughout the Testing Library docs

[grahamalama]

Are we intentionally leaving the re-render logic in there for authForm tests for now? I am curious as to how replacing that would look.

Yeah, for now I only did replacements where dropping in screen was relatively straightforward. There were a few special cases that probably deserve to be looked at in another PR