The test application now prints in a loop the input character. In case
stdin is not ready yet after startup this lets the possibility to try to
send several time a character before failing.
The automatic test is now more robust on platforms where stdin takes
time before it gets in a ready state (some AVR, hifive).
- Define test_utils_interactive_sync as DEFAULT_MODULE in Makefile.tests_common
- For tests disabling autoinit, add test_utils_interactive_sync to main
- Add DISABLE_MODULE += test_utils_interactive_sync for tests requiring
sudo, `tests/shell`, `tests/minimal` and `tests/stdin`
- Add shell_commands to tests/periph_wdt and tests/struct_tm_utility to
pull `r` and `s` commands
- Remove includes and usage in `tests/main.c` for tests that where
already using test_utils_interactive_sync
