Describe in testing documentation to build JS assets
## Description
Currently in the patch test and testing a provider we do not specify that you need to build UI assets to test certain parts. We should document this.
## Tasks
* [x] Change the testing_an_ai_provider so that the structured chat test clearly states that the JSON Schema Editor has to be built for it to work.
* [x] Change the full_patch_test documentation so it clearly has a build step if you are on dev branches.
## Acceptance criteria
* The two tasks above is fulfilled.
## Testing instructions _(added by implementor before review)_
1. Check so the documentation is changed
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issue