Feature: API for task run counts by state

[znicholasbrown]

This PR introduces a new route to the UI-API that counts task runs by state according to a given Union filter set. The intent is to fulfill the requirements for #12102, though the implementation is more generic, allowing us to pass any union filter.

Example

Hitting: /api/ui/task_runs/count with or without a union filter returns:

{
  "COMPLETED": 0,
  "FAILED": 0,
  "PENDING": 0,
  "RUNNING": 0,
  "CANCELLED": 0,
  "CRASHED": 0,
  "PAUSED": 0,
  "CANCELLING": 0,
  "SCHEDULED": 0,
}

Checklist

• This pull request references any related issue by including "closes <link to issue>"
  • If no issue exists and your change is not a small fix, please create an issue first.
• This pull request includes tests or only affects documentation.
• This pull request includes a label categorizing the change e.g. maintenance, fix, feature, enhancement, docs.

For new functions or classes in the Python SDK:

• This pull request includes helpful docstrings.

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[chrisguidry]

Solid!

[znicholasbrown]

I think I might be missing something about how to set up fixtures for postgres (or maybe my implementation is incorrect) - anyone able to help me get these tests in a good state?

[serinamarie]

I'm wondering why the tests are failing, is that the case locally?

Do we need to commit these, e.g.
await session.commit()?

[znicholasbrown]

Oo maybe that's the missing piece

[serinamarie]

LGTM!

[znicholasbrown]

can't believe that's all it was missing, you're a genius @serinamarie, thanks for the help!