[feature]: Invite non-workspace members directly to project

Is there an existing issue for this?

• I have searched the existing issues

Summary

We're currently in the process of inviting our clients as guests to their respective projects in Plane.
However, because we cannot add members to a project unless they are already in the Plane Workspace, it requires more manual effort than should be needed in my opinion.

We already know at the time of sending the invite which project the member should be granted access to. It would be great if we can create Workspace invitations directly from the project, so the member gets access to the project as soon as they join the Workspace.

Why should this be worked on?

This would be a major quality-of-life improvement, as it would eliminate an entire manual (and often repetitive) task.