Added proxy options for PSR-7 Service

[MaticSulc]

What does it do?

It uses the MODX proxy system settings for the PSR-7 service.

Why is it needed?

When behind a proxy, this allows search/listing of Extras.

How to test

Set all required proxy settings, open the Extras manager. If access to the Internet is only available via a proxy, it should work as expected.

Related issue(s)/PR(s)

Resolves #16538

[MaticSulc]

Regarding the system setting proxy_auth_type, I have not found how to use NTLM authentication type - so I didn't include it in this PR.

[opengeek]

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[MaticSulc]

Thank you for your contribution! Before your pull request can be reviewed, please sign the MODX Contributor License Agreement (CLA). This is to ensure MODX has your written permission to distribute projects containing your contributions under the appropriate license.

Please make sure the CLA has been signed for GitHub user(s): @MaticSulc

Once you've signed, please reply with a comment letting us know so we can verify.

Signed it! :)