Fail Fast control for with item task

Currently the incomplete items in a task's with list won't be processed if there are no active task item and parent task has failed status. For example let's consider this workflow

version: 1.0

description: A workflow demonstrating with items and concurrent processing.

input:
  - members  # [0,1,2,3]
  - concurrency: 1

tasks:
  task1:
    with:
      items: <% ctx(members) %>
      concurrency: <% ctx(concurrency) %>
    action: core.local cmd="[ item() -eq  1 ] && exit 1 || exit 0"

If we run above workflow it will process items 0 and 1 only, as on member 1 action will fail which will set the task1 status as fail and the concurrency is set to 1 there for there will be no active task item and state of task1 will be set to failed from running. And no other item will be processed.

With this change I have introduce a boolean parameter failfast in task which will decide wether to fail the entire task if there are not active task item and task status is failed.

version: 1.0

description: A workflow demonstrating with items and concurrent processing.

input:
  - members  # [0,1,2,3]
  - concurrency: 1

tasks:
  task1:
    failfast: false
    with:
      items: <% ctx(members) %>
      concurrency: <% ctx(concurrency) %>
    action: core.local cmd="[ item() -eq  1 ] && exit 1 || exit 0"

@exp-vkishore would you be able to revisit this? What do you think of @m4dcoder 's suggestion of a flow: keyword under with:?

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