[cmake] using cmake -E echo instead of shell echo command (#6175)

The echo command of the host system may have slight variations between
shell built-in echo and the echo command provided by the OS.

Especially the Windows OS echo command is different from practical any
other echo command.

This means that the currently used `COMMAND echo -e "<text>"` does not
work universally.

This commit introduces `etc/cmake/print.cmake` which allow to print a
CMake list where each item is printed on a new line, to get the desired
behavior on the `print-ot-config` target.

Using `cmake -E echo <text>` ensures identical behaviour across
different systems.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

CMakeLists.txt

@@ -194,4 +194,8 @@ endif()
 
 add_subdirectory(tests)
 
-add_custom_target(print-ot-config ALL COMMAND echo -e "$<JOIN:$<TARGET_PROPERTY:ot-config,INTERFACE_COMPILE_DEFINITIONS>,\"\\n\">")
+add_custom_target(print-ot-config ALL
+                  COMMAND ${CMAKE_COMMAND}
+                  -DLIST="$<TARGET_PROPERTY:ot-config,INTERFACE_COMPILE_DEFINITIONS>"
+                  -P ${PROJECT_SOURCE_DIR}/etc/cmake/print.cmake
+)