Feature/delay event processing

[avtolstoy]

Fixes issue #1055

system_delay_ms should not use !system_thread_get_state(NULL) to determine whether to run event loop or not, as it is still possible to create a thread with SYSTEM_THREAD(DISABLED) and execute delay() in that thread, which will cause the event loop to be processed from that thread:
https://github.com/spark/firmware/compare/feature/delay-event-processing?expand=1#diff-de0a60700cd1e842d6a89faaba614c8cL446

This PR:

• Changes system_delay_ms condition to if ((!PLATFORM_THREADING || APPLICATION_THREAD_CURRENT()) && !HAL_IsISR())
  • !system_thread_get_state(NULL) -> !PLATFORM_THREADING
• Exposes APPLICATION_THREAD_CURRENT()/SYSTEM_THREAD_CURRENT() macros as application_thread_current/system_thread_current dynalib functions
• Adds wiring/threading_no_threading_delay test

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Doneness:

• Contributor has signed CLA
• Problem and Solution clearly stated
• Code peer reviewed
• API tests compiled
• Run unit/integration/application tests on device
• Add documentation (N/A)
• Add to CHANGELOG.md after merging (add links to docs and issues)

BUGFIX

• Do not run the event loop from delay() when threading is enabled. Fixes #1055

[monkbroc]

Fantastic. Code looks good to me. Nice work coming up with such a detailed test.