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/gitsshkey_test.go

@@ -105,7 +105,7 @@ func TestAgentGitSSHKey(t *testing.T) {
 	})
 	project := coderdtest.CreateTemplate(t, client, user.OrganizationID, version.ID)
 	coderdtest.AwaitTemplateVersionJob(t, client, version.ID)
-	workspace := coderdtest.CreateWorkspace(t, client, codersdk.Me, project.ID)
+	workspace := coderdtest.CreateWorkspace(t, client, user.OrganizationID, project.ID)
 	coderdtest.AwaitWorkspaceBuildJob(t, client, workspace.LatestBuild.ID)
 	daemonCloser.Close()