publish motion target as pose

[mikeferguson]

Basic Info

Info	Please fill out this column
Ticket(s) this addresses	N/A
Primary OS tested on	Ubuntu
Robotic platform tested on	N/A
Does this PR contain AI generated software?	No

---

Change motion target publisher from PointStamped to PoseStamped - this allows to actually visualize if the headings are correct:

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

[mergify]

@mikeferguson, your PR has failed to build. Please check CI outputs and resolve issues.
You may need to rebase or pull in main due to API changes (or your contribution genuinely fails).