List Builder: write tests

Overview

Example list components are given here: https://git.drupalcode.org/project/experience_builder/-/tree/0.x/tests/f...

We need to write some tests for them to make sure when they're inputted into a code component they're rendered as expected.

Proposed resolution

Either import the components with the CLI whilst setting up the test, or copy the source code in via the browser in a functional test (code components need to run the tailwind css compilation after being imported, which can't be done within PHP alone). We could export experience_builder.xb_asset_library.global along with the config for the code components but that is only valid for a fixed set of components, requires some extra cache clears when imported with a recipe, and makes the code components unreviewable/hard to modify later.