refactor: create tasks in coderd instead of frontend (#19280)

Instead of creating tasks with a specialized call to `CreateWorkspace`
on the frontend, we instead lift this to the backend and allow the
frontend to simply call `CreateAITask`.

coderd/database/dbauthz/dbauthz.go

@@ -2863,6 +2863,17 @@ func (q *querier) GetTemplateVersionByTemplateIDAndName(ctx context.Context, arg
 	return tv, nil
 }
 
+func (q *querier) GetTemplateVersionHasAITask(ctx context.Context, id uuid.UUID) (bool, error) {
+	// If we can successfully call `GetTemplateVersionByID`, then
+	// we know the actor has sufficient permissions to know if the
+	// template has an AI task.
+	if _, err := q.GetTemplateVersionByID(ctx, id); err != nil {
+		return false, err
+	}
+
+	return q.db.GetTemplateVersionHasAITask(ctx, id)
+}
+
 func (q *querier) GetTemplateVersionParameters(ctx context.Context, templateVersionID uuid.UUID) ([]database.TemplateVersionParameter, error) {
 	// An actor can read template version parameters if they can read the related template.
 	tv, err := q.db.GetTemplateVersionByID(ctx, templateVersionID)

coderd/database/dbauthz/dbauthz_test.go

@@ -1443,6 +1443,20 @@ func (s *MethodTestSuite) TestTemplate() {
 		})
 		check.Args(now.Add(-time.Hour)).Asserts(rbac.ResourceTemplate.All(), policy.ActionRead)
 	}))
+	s.Run("GetTemplateVersionHasAITask", s.Subtest(func(db database.Store, check *expects) {
+		o := dbgen.Organization(s.T(), db, database.Organization{})
+		u := dbgen.User(s.T(), db, database.User{})
+		t := dbgen.Template(s.T(), db, database.Template{
+			OrganizationID: o.ID,
+			CreatedBy:      u.ID,
+		})
+		tv := dbgen.TemplateVersion(s.T(), db, database.TemplateVersion{
+			OrganizationID: o.ID,
+			TemplateID:     uuid.NullUUID{UUID: t.ID, Valid: true},
+			CreatedBy:      u.ID,
+		})
+		check.Args(tv.ID).Asserts(t, policy.ActionRead)
+	}))
 	s.Run("GetTemplatesWithFilter", s.Subtest(func(db database.Store, check *expects) {
 		o := dbgen.Organization(s.T(), db, database.Organization{})
 		u := dbgen.User(s.T(), db, database.User{})