Command for updating git submodules should be on one line (IDFGH-11663)

[georgik]

Scenario

Scenario: Update of ESP-IDF from git requires update of submodules.
ESP-IDF correctly notify users that the update is necessary.
Problem is that command is splitted into two lines which makes it harder to copy-and-paste the command.
Current situation:

CMake Warning at /Users/georgik/projects/esp-idf/tools/cmake/git_submodules.cmake:52 (message):
  Git submodule components/openthread/openthread is out of date.  Run 'git
  submodule update --init --recursive' to fix.

Desired state

Desired output:

CMake Warning at /Users/georgik/projects/esp-idf/tools/cmake/git_submodules.cmake:52 (message):
  Git submodule components/openthread/openthread is out of date.  Run following command to fix: 
git submodule update --init --recursive