Move functions using templates to *_impl.h header files.

4 jobs from clean_up_task in 3 minutes 34 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #2854
build_cmake

00:41

 
  Test
passed #2855
run_tests

00:40

 
  Sanitizer
passed #2857
run_address_sanitizer

01:15

passed #2856
run_thread_sanitizer

00:57