Fix selector attributes

[timgl]

Changes

Closes #1409. Filtering selectors with attributes wasn't working, because we are storing all attributes with the attr__ prefix. I had to use Django's "extra" function as using normal filtering didn't work.

Checklist

• All querysets/queries filter by Team (if this PR affects any querysets/queries)
• Backend tests (if this PR affects the backend)
• Cypress E2E tests (if this PR affects the front and/or backend)

[mariusandra]

Checked and it works for me!

Though I'm somewhat confused here - I thought we actually shouldn't capture any data-* attributes? Isn't that how mixpanel got in trouble?

That being said, I might be in favour of adding a separate "data-attr" that we do always capture... and even use it in the selectors when it's available. I'm intrigued by the idea of being able to add "hints" that posthog picks up to provide better element identification, though I'm not yet 100% convinced that this is what we should do. Perhaps 100% autocapture with an AI-powered simmer is a better approach? 🤔

[timgl]

Mixpanel primarily got in trouble by capturing attributes on input fields, which we don't do. I don't think data attributes are worrying.

[mariusandra]

Right. I think it was data attributes on input fields that got them in trouble. (Quote: "This change placed copies of the values of hidden and password fields into the input elements’ attributes, which Autotrack then inadvertently received.")

I guess it's fine to capture data attributes on buttons.