pw_thread_freertos/util: Don't skip the priority=0 ready tasks
pw_thread_freertos/util: Don't skip the priority=0 ready tasks

Unlike FreeRTOS upstream's uxTaskGetSystemState implementation,
we'd like to be able to report on the state of the IDLE task and
any of the user's tasks at that same priority level in case
configIDLE_SHOULD_YIELD is used.

Ergo the thread iteration is changed to include reporting active
threads at priority 0.

No-Docs-Update-Reason: No API change.
Change-Id: I7485457d4dfafb19bd495f31658429acbbd36e9f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/65860
Reviewed-by: Kevin Zeng <8f94af959dbcb7b38b98ffce1297e7efd97d4d1c@google.com>
Reviewed-by: Armando Montanez <97ef6fdb231c129ac8827d9f0c4106bfbf57f74f@google.com>
Commit-Queue: Auto-Submit <14637eda5603879df170705285bf30f5996692f0@pigweed.google.com.iam.gserviceaccount.com>
Pigweed-Auto-Submit: Ewout van Bekkum <638f134dbc68778d6b859fb04a64baea2b00b021@google.com>

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