While zone evaluate the condition tasks

[superstar54]

This PR moves the conditional task outside the zone. This simplifies the workgraph construction.

The logic to run the While Task

• All input tasks ready, including the conditional tasks
• Run the while, check the value of the conditional task, and check if the conditions are fulfilled.
• If yes, set the task state to Running, and continue the workgraph, thus its child tasks can be run.
  • when any child task is finished, it will update the state of the While task
  • When all the child tasks are finished, current iteration finished. Reset all children's tasks inside the zone and all its input conditional tasks, also the while task itself.
  • WorkGraph runs the next iteration.
• If no, set the task state to finished, and skip all its child tasks

Here is an example of the nest while zones

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.09524% with 5 lines in your changes missing coverage. Please review.

Project coverage is 79.30%. Comparing base (5937b88) to head (8e0d8db). Report is 36 commits behind head on main.

Files	Patch %	Lines
aiida_workgraph/engine/workgraph.py	78.26%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #241 +/- ## ========================================== + Coverage 75.75% 79.30% +3.55% ========================================== Files 70 62 -8 Lines 4615 4577 -38 ========================================== + Hits 3496 3630 +134 + Misses 1119 947 -172 ``` | [Flag](https://app.codecov.io/gh/aiidateam/aiida-workgraph/pull/241/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | Coverage Δ | | |---|---|---| | [python-3.11](https://app.codecov.io/gh/aiidateam/aiida-workgraph/pull/241/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | `79.17% <88.09%> (+3.51%)` | :arrow_up: | | [python-3.12](https://app.codecov.io/gh/aiidateam/aiida-workgraph/pull/241/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | `79.20% <88.09%> (?)` | | | [python-3.9](https://app.codecov.io/gh/aiidateam/aiida-workgraph/pull/241/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam) | `79.24% <88.09%> (+3.50%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam#carryforward-flags-in-the-pull-request-comment) to find out more.

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