[pose_broadcaster] Check for valid pose before attempting to publish a tf for it (backport #1479)

[mergify]

Deactivate the controller otherwise

When using the pose_broadcaster e.g. with mock hardware, the pose state interfaces might not contain any value (NaN), if there are no initial values inside the URDF. However, it might not make sense to set an initial value as this would be plain wrong information. Imagine a robot-calculated forward kinematics that generates that pose. Initializing this to any fixed value will just be wrong. IMHO it would be better to explicitly state that there is no valid information available.

Currently, attempting to publish a tf with no pose information will result in spamming the shell with

TF_NAN_INPUT: Ignoring transform for child_frame_id "tool0_controller" from authority "Authority undetectable" because of a nan value in the transform (nan nan nan) (nan nan nan nan)

In this PR I added a check for a valid pose before attempting to publish a tf and return an error in case of an invalid pose.

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This is an automatic backport of pull request #1479 done by Mergify.

[mergify]

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Changes to be committed:
	modified:   pose_broadcaster/src/pose_broadcaster.cpp
	modified:   pose_broadcaster/test/test_pose_broadcaster.cpp

Unmerged paths:
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	both modified:   pose_broadcaster/test/test_pose_broadcaster.hpp

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[saikishor]

LGTM

Thanks for fixing the API calls