roachtest: add groups to test framework

This change groups the default options used by tasks and groups into a function
that can be shared when creating new groups or tasks via the test framework. The
`Test` interface now implements `GroupProvider` as well to enable grouping
tasks.

Informs: cockroachdb#118214

Epic: None
Release note: None

pkg/cmd/roachtest/cluster_test.go

@@ -144,6 +144,10 @@ func (t testWrapper) Go(_ task.Func, _ ...task.Option) {
 	panic("implement me")
 }
 
+func (t testWrapper) NewGroup() task.Group {
+	panic("implement me")
+}
+
 var _ test2.Test = testWrapper{}
 
 // ArtifactsDir is part of the test.Test interface.

pkg/cmd/roachtest/test/test_interface.go

@@ -83,6 +83,7 @@ type Test interface {
 
 	Go(task.Func, ...task.Option)
 	GoWithCancel(task.Func, ...task.Option) context.CancelFunc
+	NewGroup() task.Group
 
 	// DeprecatedWorkload returns the path to the workload binary.
 	// Don't use this, invoke `./cockroach workload` instead.

pkg/cmd/roachtest/test_impl.go

@@ -688,21 +688,33 @@ func (t *testImpl) IsBuildVersion(minVersion string) bool {
 	return t.BuildVersion().AtLeast(vers)
 }
 
-func panicHandler(_ context.Context, name string, l *logger.Logger, r interface{}) error {
-	return fmt.Errorf("test task %s panicked: %v", name, r)
+// defaultTaskOptions returns the default options for a task started by the test.
+func defaultTaskOptions() []task.Option {
+	return []task.Option{
+		task.PanicHandler(func(_ context.Context, name string, l *logger.Logger, r interface{}) error {
+			return fmt.Errorf("test task %s panicked: %v", name, r)
+		}),
+	}
 }
 
 // GoWithCancel runs the given function in a goroutine and returns a
 // CancelFunc that can be used to cancel the function.
 func (t *testImpl) GoWithCancel(fn task.Func, opts ...task.Option) context.CancelFunc {
-	return t.taskManager.GoWithCancel(fn, task.PanicHandler(panicHandler), task.OptionList(opts...))
+	return t.taskManager.GoWithCancel(
+		fn, task.OptionList(defaultTaskOptions()...), task.OptionList(opts...),
+	)
 }
 
 // Go is like GoWithCancel but without a cancel function.
 func (t *testImpl) Go(fn task.Func, opts ...task.Option) {
 	_ = t.GoWithCancel(fn, task.OptionList(opts...))
 }
 
+// NewGroup starts a new task group.
+func (t *testImpl) NewGroup() task.Group {
+	return t.taskManager.NewGroup(defaultTaskOptions()...)
+}
+
 // TeamCityEscape escapes a string for use as <value> in a key='<value>' attribute
 // in TeamCity build output marker.
 // See https://www.jetbrains.com/help/teamcity/2023.05/service-messages.html#Escaped+Values