Fix unexpected behavior of docking when already in charger

[ajtudela]

---

Basic Info

Info	Please fill out this column
Ticket(s) this addresses	#4447
Primary OS tested on	(Ubuntu 22.04)
Robotic platform tested on	Morphia robot
Does this PR contain AI generated software?	No

---

Description of contribution in a few bullet points

• Check if the robot is in the charging station before try to dock / undock to prevent docking when it's already in the charging station and undocking if is not docked.

The fix just return, aborting the handle. It can be improve addind result / error code if necessary.

Description of documentation updates required from your changes

---

Future work that may be required in bullet points

For Maintainers:

• [ ] Check that any new parameters added are updated in docs.nav2.org
• [ ] Check that any significant change is added to the migration guide
• [ ] Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• [ ] Check that any new functions have Doxygen added
• [ ] Check that any new features have test coverage
• [ ] Check that any new plugins is added to the plugins page
• [ ] If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[SteveMacenski]

@ajtudela you need to fix the unit tests

[ajtudela]

For some reason, some tests in opennav_docking were not passing, so I forgot to check the tests in this repo. It should pass them now.

[SteveMacenski]

Great, thanks!