Support Payload api route config

[mzronek]

The current implementation always uses /api as base path for all Payload routes. This will produce an invalid spec if the Payload config uses routes.api to customize the api route path. This PR fixes the issue and adds the possibility to customize it completely.

[janbuchar]

Hi @mzronek and thanks for your contribution! How does this compare to #76?

[mzronek]

@janbuchar Glad to support the project!

Unfortunately I missed this PR. It is very close to mine. The only difference is, that my approach allows the apiBasePath to bet set freely in the plugin options. Otherwise it defaults to the currently configured Payload api route. Sorry for any inconvenience.

I updated my PR, because I liked the idea of the previous PR to use the sanitized payload config from the req object to avoid hardcoding "/api". I also added a second test to properly test changes to the Payload config.
In addition I added the correct Zed config to be able to work correctly with Biome. Without the correct Zed setup even running yarn lint:fix can't undo small style changes for long lines due to introduced commas.