Add alternative context switch implementation (similar to boost).

4 jobs from coninuation in 37 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #3444
build_cmake

00:21

 
  Test
failed #3445
run_tests

00:16

 
  Sanitizer
skipped #3447
run_address_sanitizer
skipped #3446
run_thread_sanitizer
 
Test run_tests
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CMakeFiles/Makefile2:392: recipe for target 'app/invoke_parallel/CMakeFiles/invoke_parallel.dir/all' failed
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Makefile:140: recipe for target 'all' failed
./ci_scripts/run_tests.sh: line 9: ./bin/tests: No such file or directory
ERROR: Job failed: exit code 1