feat: Add organizations endpoint for users (#50)

* feat: Add organizations endpoint for users

This moves the /user endpoint to /users/me instead. This
will reduce code duplication.

This adds /users/<name>/organizations to list organizations
a user has access to. It doesn't contain the permissions a
user has over the organizations, but that will come in a future
contribution.

* Fix requested changes

* Fix tests

* Fix timeout

* Add test for UserOrgs

* Add test for userparam getting

* Add test for NoUser

coderd/coderdtest/coderdtest_test.go

@@ -13,5 +13,6 @@ func TestMain(m *testing.M) {
 }
 
 func TestNew(t *testing.T) {
-	_ = coderdtest.New(t)
+	server := coderdtest.New(t)
+	_ = server.RandomInitialUser(t)
 }