Add resources_lock_ lock_guards to avoid race condition when loading robot_description through topic

[saikishor]

As reported in #1442, loading the robot_description through the topic will cause a segmentation fault or some undefined behaviors as the read and write methods real-time methods are continuously executed, and when the robot description is received and the resource_manager is to be initialized, there is no lock_guard of recursive mutex resources_lock_, which should avoid the RM to execute the components when they are changing state or being loaded and initialized

Fixes #1442

[christophfroehlich]

LGTM

[firesurfer]

@saikishor I just tested this PR and it seems like the treading/lock issue is gone.
I couldn't test is further as I am running iron on my system and something about the default controllers seems to have changed between iron/rolling.

It can not load the JointStateBroadCaster what(): Failed to load library /opt/ros/iron/lib/libjoint_state_broadcaster.so which is installed from the package repository.
But I guess that is to be expected.

[saikishor]

It can not load the JointStateBroadCaster what(): Failed to load library /opt/ros/iron/lib/libjoint_state_broadcaster.so which is installed from the package repository.
But I guess that is to be expected.

I believe this is related to the ABI/API breaking changes. If you are using this branch directly in rolling, then you would also need to use the master branch of ros2_controllers, control_msgs, and control_toolbox packages