Allow plugins to override blacklisted trades

[Rudokhvist]

Checklist

• [x] I read and understood the Contributing Guidelines.
• [x] This is not a duplicate of an existing merge request.
• [x] I believe this falls into the scope of the project and should be part of the built-in functionality.
• [x] My code follows the code style of this project.
• [x] I have added tests to cover my changes, wherever they are necessary.
• [x] All new and existing tests pass.

Changes

Allows plugins to review and accept trades from blacklisted users. Main reason for this change is to allow blacklisting master/owner account(s), so that instead of all trades accepted unconditionally ASF only accepted trades according to logic in plugins. This is a follow-up for https://github.com/JustArchiNET/ArchiSteamFarm/commit/1cb1bd3d67508366101ae61226c93b91526350fb#

New functionality

Allows plugins to review and accept trades from blacklisted users.

Changed functionality

Allows plugins to review and accept trades from blacklisted users.

Removed functionality

none

Additional info

Main reason for this change is to allow blacklisting master/owner account(s), so that instead of all trades accepted unconditionally asf only accepted trades according to logic in plugins.

[JustArchi]

LGTM, thanks! 🏆