feat: Allow making a workspace for another user as an admin

[Emyrk]

What this does

Adds a --user on creating a workspace for another user. Must be an admin/manager to do this.

Admin flow

Create a workspace for a user

coder workspaces create test --cpu 1 --disk 1 --memory 1 --image ubuntu --user [email protected]

Watch it build

coder workspaces watch-build base-img --user [email protected]

View the workspace

coder workspaces ls --user [email protected] 

Delete the workspace

coder workspaces rm --user [email protected] test

[shortcut-integration]

This pull request has been linked to Clubhouse Story #13817: As an admin, I can use the Coder API to create workspaces on behalf of users.