testing/ostest: Exercise custom work queues.

[13022591351]

Summary

• Extend the existing ostest work queue coverage to dynamically created
  queues with one and two workers.
• Run scheduler queues and custom queues in Flat builds, and libc custom user
  queues in non-Flat builds.
• Add ostest wqueue as a focused entry without changing the original
  no-argument ostest flow.
• Cover explicit caller priorities, invalid arguments, periodic requeue,
  pending replacement, synchronous and parallel cancellation, multiple
  simultaneous queues, self-destruction rejection, and teardown.
• Check work queue and semaphore API results and release all local test
  resources.
• Depends on wqueue: Support custom user work queues. nuttx#19982.

Impact

• New feature: YES, test coverage for custom scheduler and libc user work
  queues.
• User adaptation: NO. The no-argument ostest sequence remains unchanged
  in non-Flat builds; the focused test is selected with ostest wqueue.
• Build process: NO. CONFIG_TESTING_OSTEST_WQUEUE defaults to enabled
  only when its pthread and work queue dependencies are available.
• Hardware: NO production hardware behavior is changed.
• Documentation: NO separate application documentation is required; the
  Kconfig help describes backend selection.
• Security: NO impact.
• Compatibility: Existing Flat ostest work queue coverage is retained and
  expanded.

Testing

Build host:

• Linux 6.8.0-60-generic, x86_64
• GNU Arm Embedded Toolchain 10.3.1 20210824

Target:

• ARM Cortex-M7, STM32H7, PX4 FMUv6C
• Apache nuttx-apps master 48ddaadad1499404addd891190f64cccf50008b2
• Apache NuttX master plus wqueue: Support custom user work queues. nuttx#19982

Before change:

The ostest work queue source is selected only with CONFIG_SCHED_WORKQUEUE.
It has no focused command entry and cannot exercise libc custom user queues
in a Protected user process.

Build output after change:

master_flat:
  FLASH     1470396 B / 1920 KB (74.79%)
  AXI_SRAM    63380 B / 512 KB  (12.09%)

master_protected user:
  uflash      751000 B / 1 MB   (71.62%)
  usram         8192 B / 384 KB (2.08%)

Runtime output summary:

nsh> time "ostest wqueue"

Flat runs:
  30.1490 / 30.1490 / 30.1480 s

Protected libc user runs:
  15.6540 / 15.6540 / 15.6540 s

Every run:
  API validation done
  periodic calls = 3, expect = 3
  replacement total = 2, expect = 2
  sync cancel finished = 1, expect = 1
  parallel callbacks = 2, expect = 2
  multiple queues loop 1/4 through 4/4 done
  self free result = -35, expect = -35
  pending callback = 0, expect = 0
  running callback = 1, expect = 1
  teardown requeue rejected
  teardown done

All three runs for each backend completed without assertion. Current heap
usage did not increase after the first run, and all custom workers exited.

Validation:

checkpatch commit messages: pass
checkpatch complete patch range: pass
full-file nxstyle for wqueue.c and ostest_main.c: pass
cmake-format: pass
git diff --check: pass

PR verification Self-Check

• This PR introduces only one functional change.
• I have updated all required description fields above.
• My PR adheres to the contributing guidelines and coding standard.
• My PR is still work in progress.
• My PR is ready for review and can be safely merged.