feat: Move workspaces under organizations (#1109)

This removes split ownership for workspaces. They are now
a resource of organizations and have a designated owner,
which is a user.

This enables simple administration for commands like:
- `coder stop ben/dev`
- `coder build logs colin/arch`

or if we decide to allow administrators to access workspaces,
they could even SSH using this syntax: `coder ssh colin/dev`.

coderd/database/migrations/000003_workspaces.up.sql

@@ -5,6 +5,7 @@ CREATE TABLE workspaces (
     -- Use ON DELETE RESTRICT so that we can cleanup external workspace
     -- resources first.
     owner_id uuid NOT NULL REFERENCES users (id) ON DELETE RESTRICT,
+    organization_id uuid NOT NULL REFERENCES organizations (id) ON DELETE RESTRICT,
     template_id uuid NOT NULL REFERENCES templates (id) ON DELETE RESTRICT,
     deleted boolean NOT NULL DEFAULT FALSE,
     name varchar(64) NOT NULL,