(autofix) Revisit unit test gen flow

[roaga]

Perhaps it should be a fully developed step like root cause and code changes.

Idea for a flow:

• after root cause output, next to the "use suggested rc" and "propose your own" should be "test it", that has a message: "Write tests to reproduce the issue and verify the root cause?" and a button to trigger the test step instead of the fix
• test step runs with insight cards as usual
• final output is a text description of how to reproduce and a diff output of the tests. Can copy paste
• button to Find a Fix, generates fix as normal.
• outputted fix should have combined with the test diff
• if fix was called directly after the RCA step, there should be a 3rd tab to do the test flow. Then the test flow should end with the create PR button as well.