Add WordPress/Requests in autodiscovery and PSR-18/PSR-17 provider

[Art4]

Description

WordPress/Requests is a HTTP request library that is used in WordPress, but is also used as a standalone library. While Requests does not implement PSR-18 itself, they recommend to use WP-Requests-PSR18-Adapter allowing developers to use Requests as a PSR-18 HTTP client.

Full disclosure: I'm the maintainer of the WP-Requests-PSR18-Adapter library.

Example

If a project already have Requests installed, Discovery could auto-install WP-Requests-PSR18-Adapter.

Additional context

At the moment v1.2.0 implements theses interfaces:

• Psr-18 ClientInterface
• Psr-17 RequestFactoryInterface

These interfaces are partially implemented or planned:

• Psr-17 StreamFactoryInterface (partially)
• Psr-17 UriFactoryInterface (planned)

If this proposal is accepted I'd be glad to open a PR.