Add mechanism to determine if a task should fail the Sign Up

[harveysanders]

Is your feature request related to a problem? Please describe.
Some tasks that run during the SignUp process should not cause the entire Sign Up to fail
Ex:

• The SMS reminder
• SNAP event webhook

Describe the solution you'd like
Add some way to describe a task as required or not. If a task is not required and it fails, the Sign Up will still complete successfully with an OK response.

Describe alternatives you've considered

• Add a method to the task interface, isRequired() bool that each task can implement. Then the task runner can use this method to determine if the Sign Up request should fail if the task fails.

Additional context