Allow showing NotReady tasks in flow run graph

[EmilRex]

First check

• [X] I added a descriptive title to this issue.
• [X] I used the GitHub search to find a similar request and didn't find it.
• [X] I searched the Prefect documentation for this feature.

Prefect Version

2.x

Describe the current behavior

Tasks that are created but not executed aren't shown on the flow run graph. This is probably expected behavior, however in some cases can be useful information. For example, suppose you construct a graph ahead of time by submitting all of your tasks. It can then be helpful to see your entire graph to judge when execution stopped.

Describe the proposed behavior

Allow users to toggle whether or not to show tasks that were not run yet (i.e. in the NotReady state)

Example Use

Example of creating a graph with NotReady tasks:

import time
from prefect import flow, task

@task
def dummy(crash=False):
    if crash:
        raise ValueError("This is a dummy error")
    time.sleep(1)

@flow
def main():
    a = dummy.submit()
    b = dummy.submit(wait_for=[a], crash=True)
    c = dummy.submit()
    d = dummy.submit(wait_for=[b, c])
    e = dummy.submit(wait_for=[d])

if __name__ == "__main__":
    main()

Additional context

No response

[taylor-curran]

+1 to this

[pleek91]

I removed the UI tag from this because the UI will show them if the api returns them. The nodes are missing from the graph-v2 api response.