Add Authorization headers support to core wp-env

[Clorith]

The current nginx configuration bundled with core doesn't allow for basic auth to be passed from nginx to PHP.

With the introduction of application passwords, let's make sure those can be used when testing core as well.

Trac ticket: https://core.trac.wordpress.org/ticket/51646

[SergeyBiryukov]

In 49336:

Build/Test Tools: Add Authorization headers support to local-env.

This ensures that basic authorization is passed from nginx to PHP.

Props Clorith.
Fixes #51646.