Improve inspect context and detect undefined task logic.

[yogeshgoyal26]

Improvement in inspect context and detect undefined task logic to improve overall execution performance of inspect. Specifically scenarios where the tasks success and failure are moved to same task in the workflow, then in that case the tasks are added to the queue in multiple of 2, which increase the overall time take by inspect method.
Below is an example workflow:
Task1 - Added 1 time
Task2 - Added 2 times
Task3 - Added 4 times
Task4 - Added 8 times
..

---
version: "1.0"
description: "Test workflow"
input:
- "a1"
- "a2"
tasks:
  Task1:
    action: "core.noop"
    next:
    - when: "<% succeeded()  %>"
      do: "Task2"
    - when: "<% failed() %>"
      do: "Task2"
  Task2:
    action: "core.noop"
    next:
    - when: "<% succeeded()  %>"
      do: "Task3"
    - when: "<% failed() %>"
      do: "Task3"
  Task3:
    action: "core.noop"
    next:
    - when: "<% succeeded()  %>"
      do: "Task4"
    - when: "<% failed() %>"
      do: "Task4"
  Task4:
    action: "core.noop"
    next:
    - when: "<% succeeded()  %>"
      do: "Task5"
    - when: "<% failed() %>"
      do: "Task5"
  Task5:
    action: "core.noop"
    next:
    - when: "<% failed() %>"
      do: "fail"

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1 out of 2 committers have signed the CLA.

✅ guzzijones
❌ Yogesh Kumar

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[guzzijones]

This looks good to me.

[guzzijones]

+1 from me. This is a great find. n^2 complexity fix.

[arm4b]

@yogeshgoyal26 Looks like we have a Changelog for Orquestra: https://github.com/StackStorm/orquesta/blob/master/CHANGELOG.rst
It would be helpful to include a description for this enhancement in there too for completeness.