Add files and directories not needed for release to .distignore

[t-hamano]

I noticed that this plugin published in the plugin directory has .wp-env.json file.

https://plugins.trac.wordpress.org/browser/create-block-theme/trunk

I believe this is unnecessary for published plugins.

[vcanales]

Agreed. Should we also add test/ for good measure?

[t-hamano]

Should we also add test/ for good measure?

Makes sense. I also added vendor/ directory. Composer is not used in the current deploy action, but this is to prevent vendor directory from being unintentionally released if it is introduced in the future.

[vcanales]

LGTM! Thanks!